Satoshi Ōsugi, a university graduate, belongs to Eden of the East—a group originating as a recycling club that pivots into a technology startup developing image recognition software. He nurses an unrequited romantic attachment to fellow member Saki Morimi, fueling jealousy toward Akira Takizawa whenever Saki favors Takizawa’s presence over his plans. This resentment drives Ōsugi to publicly condemn Takizawa’s character, accusing him of orchestrating the "Careless Monday" missile attacks and kidnapping 20,000 NEETs. Evidence later proves Takizawa shielded both the missile victims and the NEETs, exposing Ōsugi’s falsehoods and humiliating him. Amid the missile crisis fallout, Ōsugi aids Saki in locating Takizawa’s mother, Aya, who operates a bar. Police—directed by Seleção Daiju Mononobe—simultaneously interrogate Aya regarding her possible ties to deceased Prime Minister Iinuma. Ōsugi’s involvement underscores his unwavering support for Saki despite her romantic disinterest. After Takizawa vanishes and Eden restructures into a formal company, Ōsugi stays with the team. He monitors Seleção activities through the game’s database and alerts Saki via text when Takizawa’s phone reactivates, fearing the game’s resurgence and warning of the Seleção system’s dangers. Ōsugi’s misfortunes include being mistaken for a criminal after Seleção Kuroha Diana Shiratori reclaims her possessions from a serial rapist who stole Ōsugi’s bag and phone during his drunken episode. This incident typifies his recurring victimization by circumstance. Within Eden, he provides operational support and bolsters group cohesion during investigations into Takizawa’s whereabouts or Seleção plots.