Hiroshi is a boy, a bit lazy in school and in his daily tasks. One day, fighting against his bullies classmates, Hiroshi accidentally fell over a frog who was jumping through Nerima, Tokyo Shakujii Park. Due to this incident, Pyonkichi, the frog, became a “flat frog” and his image and spirit get impregnated on Hiroshi’s t-shirt. Due to this shirt being the only one that Hiroshi has kept in good shape, he is forced to wear it everyday, interacting with Pyonkichi and becoming friends.