Kojima is the cleanup batter in the professional baseball team, Saikyou Saitama Lycaons. He is defeated by Toua during his time at the training camp as he challenged Toua to avenge his relief pitcher, Nakane. After his defeat, he goes into the forest to train himself mentally against Toua but as he is training he injures his wrist. Even with the injury he challenges Toua to a rematch with the bet that if he wins, he takes Toua's hand. He wins the match as he gets hit by the pitch making it a dead ball; Toua admits defeat and Kojima makes Toua join the Lycaons.