When Toan arrived in Muska Lacka, Gosuke mentioned that he wasn't feeling well. When the georama on Toto's house is completed, Gosuke is shown lying on the floor, with Toto next to him. Gosuke tells Toto that his mission will be accomplished when he dies. Toto doesn't want him to leave, because he's his only friend. Gosuke tells Toto he is going to be reborn as a human, and he promises he will visit Toto. His eye closes, and a light emits from the body, and where the body was, the Sun Sword appears. Toto tells Toan that it must be his.
Gosuke is said to be sent by Toan's father, Aga. The Sun Sword was a "treasure" that was meant for Toan.