Lonely thirty‑seven‑year‑old Satōru Mikami is stuck in a dead‑end job. Earthly life no longer brings him joy. However, after dying at the hands of a robber, Satōru gains a new life and wakes up in a fantasy world; only now he is… a slug! Having grown accustomed to his new formless state, Satōru sets out on adventures that become the beginning of a chain of events that will forever change his new world.