Hiyoko Hoshino (Aika Hirota) dreams of becoming a princess of the cookie world. One day, she is sucked into a donut hole and arrive in an animated world. She meets a girl named Tamako-chan and the creature Kokkubo. Hiyoko Hoshino visits the animation world everyday, but Tamako-chan dwells in Hiyoko Hoshino's body. Then, Tamako-chan enters this world and they begin to live in turns.

Underground people who exhale toxic gas appear in Tokyo's S-Ward, which is dealing with construction noise from urban development projects. Everyone panic, but it turns out that five middle-aged guys are unaffected by the poisonous gas. They undergo vigorous training to fight the underworld people, but are they going to be able to save the world…?

Story follows high school student Saki Miyanaga and her classmates as they become absorbed in the game of mahjong. They target an upcoming national competition.