OWL-4 redirects here, specifically to the History subsection FedCom Civil War.
Yorii 3151.svg
System Information
X:Y Coordinates-8.015 : 21.153[e]
Spectral classF6V[1]

The Yorii system was home to at least one habitable world, Yorii I, and as of June 3152 was located in the Vega Protectorate within the Rasalhague Dominion.[2]

System Description[edit]

The Yorii system is located near the Killbourn and Rocky systems[3] and consists of a class F6V primary orbited by five planets, at least one of which is habitable.[1]

System History[edit]

The Yorii system was colonized during the First Exodus from Terra and remained a member of the Terran Alliance even after the Demarcation Declaration.[4]

Political Affiliation[edit]

Yorii I[edit]

Yorii I
Orbital view
Orbital view
System position First[1]
Jump point
14 days[1]
Moons None[1]
Surface gravity 1.12[1]
Atmospheric pressure Standard (Breathable)[1]
Equatorial temperature 40°C[1]
Surface water 81%[1]
Highest native life Reptiles[1]
Reference Year 3130[1]
Ruler Darius Leveraux, Governor (3130)[64][1]
Ophelia Rossem, Legate (3130)[64][1]
Capital Neo-Tokyo (2750);[1]
Shenobi (3130)[1]
Population 1,538,000,000 (3130)[64][1]

Yorii I - more commonly referred to simply as Yorii - is the first of five planets in the Yorii system.[1]

Planetary History[edit]

Early History[edit]

The first colonists on Yorii were faced with a range of problems including the high gravity, aggressive wildlife and the incompatibility of most Terran crops with the various soils found on the planet. None of these problems proved completely insurmountable; the colonists established communities on three of the four island continents on the planet, creating thriving industrial and mining communities on each. The basis of the planetary economy became the heavy metal deposits located on the planet, many of which had to be accessed by offshore drilling platforms. A number of hybrid food crops were created that could grow on Yorii and these swiftly became the dietary staples of the majority Asian population. The colonists even managed to reduce the threat posed by the dominant native species, the Yoriian tiger-raptor, by building high walls around their settlements and farmlands on Yokohama, the continent most heavily populated by tiger-raptors. A hunting initiative aimed at reducing the population of tiger-raptors brought the dangerous reptilian predator under control in less than ten years.[1] Yorii was one of the worlds that remained a part of the Terran Alliance following the Outer Reaches Rebellion and the Demarcation Declaration of 2242,[4] and became one of the worlds within the Alliance Core region of the Terran Hegemony.[12]

Star League Era[edit]

During the era of the Star League the capital city of Yorii, Neo-Tokyo, was the site of significant commercial trading between the Draconis Combine and the Terran Hegemony. Located on the shore of Shokaku, Yorii was such a notable haven for trade between the two states that a substantial portion of the city's population were of dual nationalities, holding citizenship in both states.[1] Yorii was also a minor mining and industrial center.[65]

Yorii was badly damaged during the Amaris Civil War; when the Star League Defense Force launched its campaign to liberate the planet the defending Amaris Empire Armed Forces units resorted to using the cities as battlegrounds, along with many of the industrial complexes located across the world. The damage inflicted during the AEAF defense killed millions and left millions more homeless as well as ravaging both Yorii's industrial base and its economy; Neo-Tokyo was rendered utterly uninhabitable at the end of the campaign as the last of the AEAF troops holding out on the planet sabotaged the fusion reactor that powered the city in an effort to create a distraction to mask their escape attempts.[1]

Succession Wars[edit]

Quickly and easily annexed by the Draconis Combine, the Draconis Combine Mustered Soldiery used Yorii as a forward base for raids against the Capellan Confederation, Federated Suns and Lyran Commonwealth during the Succession Wars. Although Yorii was struck by various punitive raids and subject to the widespread technological and industrial declines common to the Succession Wars, the planet did slowly recover some of its former prosperity.[1]

Fourth Succession War[edit]

Following the successes achieved by the Lyran Commonwealth Armed Forces during Operation GÖTTERDÄMMERUNG, the major Lyran offensive launched in late 3028,[66] a lull settled over the front while the LCAF consolidated its gains, rested and resupplied its troops and fought with counterattacking Draconis Combine Mustered Soldiery units. General Jack Sphire, Margrave of the Ryde Theater of the Commonwealth, was responsible for devising a plan to break the deadlock on offensive operations against the combine in the Ryde area of operations. Ryde's plan, dubbed Operation HOLDUR, was designed to seize further systems by deploying all available troops, up to and including planetary militia forces. HOLDUR was risky, but Sphire hoped that by launching quick and forceful attacks using the BattleMech regiments available to him, the DCMS would be left with too little time to make further counterattacks. Archon Katrina Steiner approved the plan and mobilized additional 'Mech regiments to support HOLDUR, deploying regiments that had previously been held in reserve. When assigning these additional forces, the Archon dictated that these forces had to be used at the Terran end of the Ryde area, so that they could respond to any attacks originating from the Free Worlds League. This led Sphire to adjust his plan somewhat, but on the 1st of June 3029 Operation HOLDUR began, with the better part of a hundred assorted regiments deploying from the Federation of Skye to attack eight Combine systems.[34]

Yorii was one of the worlds targeted by Operation HOLDUR; the attack on Yorii was unusual, in that only conventional forces were deployed. Yorii was garrisoned by sixteen assorted well-trained and well-prepared DCMS armor and infantry regiments, and the battle for the planet was vigorous. The Commonwealth forces proved their worth time and again, particularly the First Muphrid Rangers, and after five months of combat drove the defending DCMS forces off Yorii in November, securing the planet for the Commonwealth.[34]

FedCom Civil War[edit]

By the end of the FedCom Civil War Yorii had begun to grow economically for the first time in centuries, bringing back a measure of prosperity to the lives of the populace.[65]

Clan Smoke Jaguar prisoners of war taken during this time in Operation SERPENT and Operation BIRD DOG[67] were detained in at least two out of four prison camps on Yorii, one of which was identified as OWL-4.[68] They would be freed during the Jihad, see below.

The Jihad[edit]

Yorii was one of four worlds captured by the Word of Blake between the 19th and 21st of June 3068. The Blakists attacked using both conventional forces and a combination of biological, chemical and nuclear weapons to complete their conquest, forcibly integrating Yorii into the Word of Blake Protectorate.[53] Several bomb blasts (determined to be large "dirty bombs") were detected in the heart of Neo-Tokyo, devastating hundreds of city blocks, destroying several power nodes, and severing two major highway arterials over the Shokaku Ocean. As emergency crews responded to the massive disaster, waves of unidentified aerospace fighters dropped several bombs on the 60-million-acre fisheries belonging to Kishi Amalgamated, releasing a chemical agent that begun to systematically destroy the fertile gorii-tuna awaiting harvesting there. As the Night Stalkers began to muster, the incoming DropShips unleashed a devastating missile attack on the island base, destroying it with multiple nuclear blasts and sending a tsunami across the Minamoto Sea that devastated the coastal croplands near Neo-Tokyo. It is unknown at this time if any Night Stalker units survived the bombardment. The death toll is estimated to be in the tens of thousands, though the greater damage is to the massive fisheries that cover almost seventy percent of the planet's oceans.[69]

The Blakist occupation reversed the marginal rebuilding that Yorii had managed to achieve during the Succession Wars[1] the invading forces were the Fourteenth Militia Division, who attacked under false colors; while they engaged the Third Night Stalkers with conventional weapons, elements of the Word of Blake's ROM department contaminated many of the reservoirs across the planet with a biological weapon. Millions of people were killed by direct exposure to the biological agent in the water; the contaminated water then worked its way into a number of irrigation systems, contaminating countless square kilometers of farmland and poisoning the crops grown there. Millions more died from eating the contaminated food grown in this tainted cropland before the planetary government burned every affected field, but the ensuing famine caused by lack of crops caused even more of the population to die.[65]

In November 3076 forces from Devlin Stone's allied coalition were on Yorii when they discovered (at least) two Blakist reeducation camps including OWL-4 from which the inhabitants, who turned out to be Clan Smoke Jaguar warriors, had already freed themselves from their captors. The Clansmen were presumed to have originally been prisoners captured by the Draconis Combine during either the battle for Huntress, Operation BULLDOG[70][71] or even the Battle of Tukayyid. The Smoke Jaguars were using Blakist equipment, and were encountered in various small groups, each of which challenged the forces from Stone's Lament and the First Kell Hounds to honor duels. Evidence discovered later indicated that the Blakists had deliberately abandoned the Smoke Jaguar prisoners in the hope that Stone's Coalition forces would destroy them; instead, Stone welcomed the former Clansmen into his forces.[65]

After the liberation of Yorii Stone led most of his forces away from Yorii, leaving behind a conventional garrison comprised of Lyran volunteers.[65] It was reported in the Lyran media by Myra Kellison of Tharkad Media Associates[72] in late March 3077 that Blakist forces, led by the Fourth Militia Division, had assaulted Yorii and recaptured the planet after destroying the defending garrison forces,[65][72] which consisted largely of Lyran Alliance infantry and armor.[72] The attack by the Fourth Militia incensed Clan Ghost Bear when they learned that a Ghost Bear merchant convoy bringing supplies intended for the Coalition garrison had been destroyed; the actions of the Blakists drove the Ghost Bears into a collective fury because of the cowardly manner in which the convoy had been attacked, and the entire of Kappa Galaxy was redeployed to not only recapture Yorii but also to root out every single Blakist nest anywhere on the planet. The Ghost Bear assault began in September 3077, and not a single Blakist survived to be taken prisoner.[65]

Dark Age[edit]

The marks left on Yorii by the Jihad were still in place half a century later; the planet began slowly recovering as a part of the Republic of the Sphere, but even as late as 3130 the various mining and manufacturing settlements across the world were struggling to reach their pre-Jihad production levels, and many of the farmlands poisoned and contaminated by the Blakists were still fallow,[1] although Republican agriculturists continued to retest the soil every five years, looking for signs the contamination was fading.[65]

During the Dark Age each of the populated continents on Yorii was home to a handful of major cities and the new planetary capital, Shenobi, was located on Yokohama.[1]

In 3135, Bannson's Raiders started stripping the mining planet of some badly needed resources, but not long after that, a large Spirit Cats contingent was reported. Both forces clashed and the Spirit Cats repulsed Bannson's Raiders.[73]

Planetary Rulers[edit]


  • Planetary Governor Darius Leveraux[1]
  • Planetary Legate Ophelia Rossen[1]

Military Deployment[edit]



  • Second Narhal's Raiders[75]


  • Narhal's Raiders[76]
  • Second Narhal's Raiders[76]





Yorii is a large world possessed of large oceans, a few veins of various mineral resources and a diverse range and variety of aggressively territorial wildlife. Yorii has noticeably higher gravity than Terra and soils that are incompatible with the majority of common Terran food crops. The largest continent on the planet is located in the southern hemisphere and was named Shokaku by the early colonists; there are at least three other major continents on the planet, consisting of Yokohama in the northeast and Khesan and Xu-Lai in the north.[1] The Shokaku Ocean surrounded the Shokaku continent.[69]

Planetary Locations[edit]

  • Neo-Tokyo: the planetary capital city up until the Amaris Civil War; located on the coast of Shokaku.[1]
  • Shenobi: the planetary capital city during the Dark Age, located on Yokohama.[1]
  • Minamoto Sea[69]
  • Shokaku Ocean[69]

Industrial Centers[edit]

Local Fauna[edit]

Map Gallery[edit]

Nearby Systems[edit]

Closest 80 systems (80 within 60 light-years)
Distance in light years, closest systems first:
Killbourn 8.6 Rocky 9.4 Asta 12.9 Imbros 14.2
Altair 18.4 Tau Ceti 18.6 Rigil Kentarus 19.3 Muphrid 20.3
Thorin 20.4 Zollikofen 21.0 Dieron 21.2 Sol 22.6
Lyons 23.1 Dyev 23.9 Ko 24.9 Chara 25.8
Athenry 27.4 Lone Star 29.5 Sirius 29.5 Lipton 29.8
Caph 30.2 Menkent 30.3 Xi Ursae Majoris 30.6 Atria 31.5
Zavijava 32.0 Procyon 32.4 Fomalhaut 33.0 Keid 33.2
Pike 33.5 Styx 34.1 Nusakan 34.7 Saffel 34.9
Graham 35.1 Chaville 36.2 Sabik 36.2 Haddings 36.7
Summer 36.8 Alkalurops 36.8 Oliver 36.9 New Home 37.1
Denebola 37.5 Bryant 40.4 New Stevens 40.8 Skondia 41.8
Carver 42.0 Lambrecht 42.3 Nirasaki 42.4 Pollux 43.6
New Britain 43.8 Moore 45.0 Devil's Rock 46.1 Mizar 46.5
Dromini 46.8 Galatea 47.6 Hechnar 48.0 Northwind 48.5
Kervil 48.9 Deneb Algedi 49.4 Afleir 49.5 Castor 49.8
Epsilon Eridani 49.9 Alioth 51.4 Zebebelgenubi 51.5 Lockdale 51.7
Nai-Stohl 52.1 Epsilon Indi 52.3 Zosma 52.6 Brownsville 53.0
Syrma 53.0 Cor Caroli 54.6 Quentin 54.7 Kuzuu 55.0
Telos 55.4 Tabit 55.5 Outreach 56.1 Alphecca 56.3
La Blon 56.9 Nashira 57.0 Skye 57.6 Milton 59.3


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 Dark Age: Republic Worlds (3130), p. 254: "Yorii"
  2. 2.0 2.1 Dominions Divided, p. 85: "Rasalhague Dominion June 3152" (Map)
  3. 3.0 3.1 Era Report: 2750, p. 37: "Inner Sphere - [2750] Map"
  4. 4.0 4.1 4.2 Handbook: House Marik, p. 16: "Free Worlds League Founding - [2271] Map"
  5. Handbook: House Kurita, p. 18: "Draconis Combine Founding - [2319] Map"
  6. Handbook: House Steiner, p. 13: "Lyran Commonwealth Founding [2341] Map"
  7. Handbook: House Liao, p. 17: "Capellan Confederation Founding - [2366] Map"
  8. Handbook: Major Periphery States, p. 18: "Rim Worlds Republic after Age of War - [2571] Map"
  9. Handbook: House Steiner, p. 25: "Lyran Commonwealth after Age of War - [2571] Map"
  10. Handbook: House Marik, p. 24: "Free Worlds after Age of War - [2571] Map"
  11. Handbook: House Kurita, p. 31: "Draconis Combine after Age of War - [2571] Map"
  12. 12.0 12.1 Historical: Reunification War, p. 159: "Inner Sphere - [2596]"
  13. Handbook: Major Periphery States, p. 25: "Rim Worlds Republic at the Fall of the Star League - [2750] Map"
  14. Field Manual: SLDF, p. xi: "Inner Sphere - [2764] Map"
  15. Historical: Liberation of Terra Volume 1, p. 10: "Inner Sphere - [2765] Map"
  16. Field Report 2765: LCAF, p. 25: "Lyran Commonwealth Armed Forces Deployment Map - [2765]"
  17. Historical: Liberation of Terra Volume 1, p. 104: "Rim Worlds Republic - [2767] Map"
  18. 18.0 18.1 Historical: Liberation of Terra Volume 1, p. 138: "Operation LIBERATION Wave 1 [July 2772 - December 2774]"
  19. First Succession War, p. 25: "Inner Sphere - [2786] Map"
  20. Historical: Liberation of Terra Volume 2, pp. 122–123: "Inner Sphere - [2822] Map"
  21. Handbook: House Steiner, p. 36: "Lyran Commonwealth after First Succession War - [2822] Map"
  22. Handbook: House Marik, p. 34: "Free Worlds after First Succession War - [2822] Map"
  23. Handbook: House Kurita, p. 43: "Draconis Combine after First Succession War - [2822] Map"
  24. First Succession War, p. 113: "Inner Sphere - [2822] Map"
  25. Handbook: House Steiner, p. 40: "Lyran Commonwealth after Second Succession War - [2864] Map"
  26. Handbook: House Marik, p. 38: "Free Worlds after Second Succession War - [2864] Map"
  27. Handbook: House Kurita, p. 53: "Draconis Combine after Second Succession War - [2864] Map"
  28. House Kurita (The Draconis Combine), foldout: "Draconic Combine Map - [3025]"
  29. Handbook: House Kurita, p. 64: "Draconis Combine after Third Succession War - [3025] Map"
  30. House Kurita (The Draconis Combine), p. 132: "District and Prefecture Boundaries of Kurita Space"
  31. House Steiner (The Lyran Commonwealth), foldout: "Lyran Commonwealth Map - [3025]"
  32. Handbook: House Steiner, p. 47: "Lyran Commonwealth after Third Succession War - [3025] Map"
  33. Handbook: House Marik, p. 42: "Free Worlds after Third Succession War - [3025] Map"
  34. 34.0 34.1 34.2 NAIS The Fourth Succession War Military Atlas Volume 2, p. 73: "Ryde Theater"
  35. Handbook: House Steiner, p. 56: "Lyran Commonwealth after Fourth Succession War - [3030] Map"
  36. Handbook: House Marik, p. 51: "Free Worlds after Fourth Succession War - [3030] Map"
  37. Handbook: House Kurita, p. 66: "Draconis Combine after Fourth Succession War - [3030] Map"
  38. Handbook: House Steiner, p. 59: "Lyran Commonwealth after War of 3039 - [3040] Map"
  39. Historical: War of 3039, p. 132: "Inner Sphere - [3040] Map"
  40. Handbook: House Kurita, p. 68: "Draconis Combine after War of 3039 - [3040] Map"
  41. Era Report: 3052, p. 11: "Inner Sphere - [3050] Map"
  42. Handbook: House Steiner, p. 61: "Lyran Commonwealth after Clan Invasion - [3052] Map"
  43. Era Report: 3052, p. 22: "Inner Sphere - [3052] Map"
  44. Handbook: House Kurita, p. 71: "Draconis Combine after Operation REVIVAL - [3052] Map"
  45. Era Report: 3062, p. 10: "Inner Sphere - [3057] Map"
  46. Handbook: House Marik, p. 54: "Free Worlds after Operation Guerrero - [3058] Map"
  47. Era Report: 3062, p. 28: "Inner Sphere - [3063] Map"
  48. Inner Sphere, p. 75: "Lyran Alliance Map"
  49. Handbook: House Steiner, p. 70: "Lyran Commonwealth after FedCom Civil War - [3067] Map"
  50. Handbook: House Marik, p. 56: "Free Worlds after FedCom Civil War - [3067] Map"
  51. Jihad: Final Reckoning, p. 42: "Inner Sphere - [3067] Map"
  52. Handbook: House Kurita, p. 74: "Draconis Combine after FedCom Civil War - [3067] Map"
  53. 53.0 53.1 Jihad: Final Reckoning, p. 45: "The Jihad in Review"
  54. Jihad Secrets: The Blake Documents, p. 65: "Inner Sphere - [3075] Map"
  55. Field Report: Clans, p. 29: "Terran Corridor Deployment Map - [August 3079]"
  56. Field Report: LAAF, p. 19: "Lyran Alliance Armed Forces Deployment Map - [August 3079]"
  57. Jihad: Final Reckoning, p. 62: "Inner Sphere - [3081] Map"
  58. Field Manual: 3085, p. vii: "Inner Sphere - [3085] Map"
  59. Era Report: 3145, p. 11: "Inner Sphere - [3135] Map"
  60. Era Report: 3145, p. 39: "Inner Sphere - [3145] Map"
  61. Field Manual: 3145, p. VI: "Inner Sphere - [3145] Map"
  62. Shattered Fortress, p. 103: "Inner Sphere - 3151" (Map)
  63. IlClan, p. 126: "Bracing for the Winds of Change"
  64. 64.0 64.1 64.2 Dark Age: Republic of the Sphere, p. 22: "Prefecture IX"
  65. 65.0 65.1 65.2 65.3 65.4 65.5 65.6 65.7 Total Chaos, pp. 160–161: "Yorii"
  66. NAIS The Fourth Succession War Military Atlas Volume 2, p. 60: "Draconis Front (January 3029)"
  67. Confirmed for POWs from Operation BIRD DOG through the ending of the short story Quail Hunting, where the captive Manfred Chrisholm is sent to OWL-4
  68. Total Chaos, pp. 160–161: "Ghost Tiger" scenario establishes OWL-4 as one of four campsites where supposed Word of Blake forces who would turn out to be former Smoke Jaguars are holed up in January 3077
  69. 69.0 69.1 69.2 69.3 69.4 Blakist Forces Employ WMDs on Altair, Yorii
  70. Jihad Hot Spots: Terra, p. 23: "Timeline of the Jihad"
  71. Jihad: Final Reckoning, p. 56: "The Jihad In Review"
  72. 72.0 72.1 72.2 Jihad Hot Spots: Terra, p. 28: "Just A Setback"
  73. 3135 PDA Journals, p. 96: "27 September 3135"
  74. 74.0 74.1 First Succession War, p. 137: "First Succession War Deployment Table - DCMS"
  75. 75.0 75.1 Historical: War of 3039, p. 141: "Deployment Table"
  76. 76.0 76.1 20 Year Update, p. 26: "Federated Commonwealth Deployment Table"
  77. 20 Year Update, p. 71: "Com Guards Deployment Table"
  78. ComStar, p. 85: "Com Guards Deployment Table"
  79. Field Manual: Updates, p. 117: "Draconis Combine Deployment Table"
  80. Field Manual: 3145, p. 144: "Republic Armed Forces - Principes Guards"
  81. First Succession War, p. 125: "Shipbuilding Casualties of the First Succession War"