Nishibe, a shy and indecisive student, finds himself on an island, initially thinking it's just a school trip. However, things take a dark turn when they learn it's the beginning of a deadly game, and only five can escape on the rescue boat arriving in 28 days. Will Nishibe overcome his uncertainty and survive this unexpectedly dangerous situation? The curtain rises on a deadly game involving cute but lethal mice.

(Source: Kodansha, translated)