The time is the near future. Cockroaches and other household pests have become immune to all forms of insecticides. In response to this crisis, a Japanese company has created small, doll-like insect exterminating robots called Hoi Hoi-san. A competing company has also released their own version, Combat-san. Because of their adorable appearance, these little robots have become somewhat of a phenomenon and have gained many fans. Late at night, in the home of one such fan, Hoi Hoi-san and Combat-san search for insects to exterminate... but Combat-san is not above trying to exterminate Hoi Hoi-san while she's at it.