Oshigamama is an abbreviation of "holding in pee." More and more people are becoming addicted to the feeling of relief when they finally let out the pee they've been holding in to the limit. [Synopsis] One afternoon, Kana is on her way home from shopping and can't find her keys at the front door, so she can't hold it in and ends up wetting herself. Her nephew Kazuya, who lives nearby, happens to see her. Ever since that day, Kazuya's shameful behavior has been burned into his mind and he can't get it out of his head, so he ambushes Kana...