Kizuki Ken is a high school boy with an unusual hobby: he builds detailed dollhouses. One morning, he opens the dollhouse he made himself only to find a palm-sized, menacing-looking man standing inside. The tiny man, who introduces himself as Ginji, claims to be from outer space and makes a request of Ken. Ginji belongs to a group of small, yakuza-like aliens called the Oniyadori-gumi, and he is in need of a new home. Ken, moved by the situation, agrees to help Ginji find or build a suitable dwelling. What follows is a comedy of daily life in which Ken’s quiet world of crafting miniature houses is turned upside down by the arrival of Ginji and other tiny, rowdy aliens who bring their own demands, traditions, and mischief. The story unfolds as Ken tries to construct a proper “shell” for Ginji, while dealing with the chaotic yet endearing antics of the miniature gangsters. Later volumes introduce additional alien visitors and escalating complications, such as a strike within the dollhouse and an unexpected visit from the group’s boss, all while Ken struggles to balance his school life and his growing responsibility for his interstellar housemates.