Rivaille Ackerman (son of Levi and Eren) with Commander Hange is trapped in the world of Haikyuu where Hange was in that world for 7 years and became a scientific teacher . Rivaille meets volleyball players in a mansion where he has to play alongside others and Rivaille did know that all people is mafia. People on Haikyuu has crush on Rivaille. Rivaille become a mafia assistant and find out that his uncle Kenny is in this world become Mafia boss