Amagoi

A boy named Sora lives with his younger sister, Ann, and their humorous father. Ann performs as a soloist at her school's chorus concert, while Sora prepares a special bento for her. During her performance, a strange force causes a tear in reality, and Ann's existence begins to dissolve. Sora rushes to save her but becomes caught in the same phenomenon. Both are pulled into a dark ritual that transports them to a fantasy world dominated by massive mushrooms. Their fates remain uncertain.