Yoshino was a Nega character, a cyborg Green Yoshi, a heroic warrior that helped the heroes early on during the current war against Shade, back when it started as a conflict with Omega and Grodus. He united the lands freed from villains with Lavalava Island as a center to the freed world, with Mt. Lavalava being transformed into a super weapon under his design, made specifically to kill Omega. After Omega and Grodus were killed and Shade took over their global forces, Yoshino fought alongside the heroes during their ensuing extremely long campaign against Shade. Eventually, however, while on a mission with his friend and fellow hero Echo, Yoshino was seemingly killed when Chaos Council member Kagetou came back to life. Yoshino had been carrying a virus fragment inside of his shell, and when Kagetou summoned all of the fragments to reform his body, Yoshino's fragment ripped straight through his body and joined with the rest of Kagetou, seemingly ending the life of Yoshino.
Years after, however, during a fight with Kagemamoru, Echo thought he heard Yoshino calling for help after landing a solid hit on the virus monster, leading him to speculate that Yoshino's soul was trapped with the virus energy and could be returned to his body. This was unable to be investigated further due to the villain escaping, unfortunately.