One day during the rainy season, a man was taking someone else's umbrella from a storefront in Bikon, when he felt a gaze and looked up to see a mysterious fish hanging from a string staring at him in the rain. It did not speak, did not move, and its expression did not change... The name of the mysterious fish was - Pisu-chan. Surrounded by the mischievous store manager, the work-ready mysterious insects, and the innocent and relentless children who come to play with her, Pisu-chan makes the store a lively place to be.