While working for Draconis Combine shipping conglomerate Isesaki Shipping, Sakamoto was arrested in 3050 by FedCom Intelligence agents for smuggling (it is unknown if the company knew of Sakamoto's smuggling activities). The rest of the crew of the JumpShip Katana and DropShip Kwaidon were also arrested during the same raid which apprehended Sakamoto, and which also saw the vessels impounded. Shortly after, then-Major Adam Steiner commandeered the impounded vessels and offered their crews amnesty and the eventual return of the vessels in exchange for providing transport for an intelligence gathering mission behind Clan lines. Franklin overcame his distrust of Adam Steiner to become one of the most valuable members of Steiner's 1st Somerset Strikers. It is rumored that Sakamoto rescued Prince Victor Steiner-Davion from an assassination attempt during his time with the Strikers. Sakamoto was also the first Inner Sphere Battle Armor trooper to destroy a Clan BattleMech (while piloting Sloth BattleArmor). Sakamoto has also demonstrated skill in BattleMech and AeroSpace Fighter piloting, in addition to some proficiency in demolitions. During his time with the 1st Somerset Strikers he was caught up, against his will, in an attempted coup against Takashi Kurita by the Black Dragon Society . The plot failed, Franklin renounced his claim to the Draconis throne, and rejoined the Strikers.
While Franklin would renounce his own claim, his great-grandaughter Yori Kurita ascended to the throne of the Draconis Combine, upon the assassination of Coordinator Vincent Kurita. Coordinator Vincent's entire family were either killed or missing at the time, leaving Yori as the only heir despite her "illegitimate" status.  
- According to Heir to the Dragon, chapter 1, his mother Kathleen Palmer had a relationship with Theodore Kurita during their days at the Wisdom of the Dragon school on Kagoshima; in the night prior to graduation (17 May 3018) they had a tryst but Theodore was then attacked by an assailant in her appartment whose mirror image he saw in her eyes and later noted she did not warn him of the man's presence. It is implied their relationship ended at this point. No pregnancy of Kathleen Palmer was mentioned, suggesting their son was born when they had already broken up. By September 3019 Theodore had already begun a relationship with Tomoe Sakade. This summarily suggests that Franklin Sakamoto was born in early 3019 or possibly late 3018.
- 1st Sommerset Strikers, p. 54
- Black Dragon (novel), p.??
- Jihad Turning Points: Luthien, p. 8, "Traitor's Kiss"
- Dragon Rising (novel), p. 296
- Era Report: 3145, p. 89, "Yori Kurita profile"