Bessho Tomoyuki served as a bushō for the Bessho clan of eastern Harima Province.
In 1560, Tomoyuki was born as the second son of Bessho Yasuharu, the head of the clan in control of eastern Harima. Despite his youthfulness, Tomoyuki was known among locals as a fierce warrior. Tomoyuki followed his older brother, Bessho Nagaharu, by opposing Oda Nobunaga. In 1578, upon orders from Nagaharu, Tomoyuki endeavored to valiantly defend a residence in Miya-no-Ue against an attack by forces under Hashiba Hideyoshi, but the effort proved to no avail, so Tomoyuki converged with 3,2000 soldiers holed up with Nagaharu in Miki Castle. During the Siege of Miki Castle, Hideyoshi executed a deprivation strategy blocking supply routes and waiting until provisions ran dry in the castle. The defenders eventually surrendered in 1580. Tomoyuki and his seventeen-year-old wife wrote death poems, whereupon he slayed her and then committed seppuku with Nagaharu’s short sword.