In this game, the player controls Mouse, a silent musician who travels with his talking guitar Pattimo. One day Mouse is invited to play at a royal wedding on an island called Pandule. But soon he discovers that the groom Xelpherpolis has put an awful time-looping spell on the island, and intends to destroy this way the entire population. Mouse has to stop the villain and, most importantly, recruit other people to help him break the spell.

Ephemeral Fantasia is a Japanese-style role-playing game with turn-based combat. Several characters can be recruited to the party. The game's stand-out feature is the time-looping system, which is somewhat similar to the one implemented in The Legend of Zelda: Majora's Mask. The game has an internal clock, and the first five days repeat themselves until Mouse finds a way to stop it. Certain events occur only if Mouse travels to a specific location at a specific time.