During a school excursion, Kaito Ise and his classmates find themselves in a deadly game where only one can survive. Unbeknownst to the organizers, Kaito is no ordinary participant—he is an 'isekai returner' who spent a decade battling fierce creatures in a fantasy realm. Despite his youthful appearance, he possesses unparalleled strength. After swiftly defeating his opponents, Kaito yearns for a quiet life, longing for normalcy amidst chaos. However, tranquility eludes him as new challenges emerge, disrupting his desire for peace and quiet.