The openly homosexual and sadistic wielder of a sneaky, retractable sword named "Jakotsutō", Jakotsu (蛇骨) is one of the more skilled fighters of the Shichi'nintai and was placed third in command. He seems to be the first of the Shichinintai to have come into contact with Bankotsu and was with him before the Shichinintai were assembled as a group. Bankotsu and Jakotsu are very close and according to Bankotsu, Jakotsu is the only person he trusts.

Upon hearing of InuYasha of news by Kohaku, Jakotsu immediately develops a bloodthirstly and slightly sexual fascination with him. He spends the majority of the arc trying to find, battle, and kill him. After meeting InuYasha, Jakotsu is frequently swooning and petulantly protesting when he is denied confrontation. He also flies into a rage when Sango interferes in his first conflict with InuYasha, and at one moment Jakotsu openly says he finds Miroku good-looking too.

Jakotsu always looks for an opportunity to fight against InuYasha. He finally gets a chance inside Mount Hakurei when InuYasha is reverted to his human form by the holy barrier. After a lengthy fight, Jakotsu loses to InuYasha (who has turned back in to a hanyō, due to the weakened barrier), who spares his life. Jakotsu happily accepted his fate that he died after fighting the battle he wanted, but could have survived if the Shikon shard embedded in his neck wasn't taken by the scheming Renkotsu, an action later avenged by Bankotsu.