In the near‑future, cockroaches and other household pests have become immune to all conventional insecticides. A Japanese company responds by creating tiny, doll‑like extermination robots called Hoi Hoi‑san. A rival firm launches its own version, Combat‑san. Their adorable designs spark a cultural phenomenon, attracting a devoted fan base. One night, in the home of a passionate admirer, Hoi Hoi‑san and Combat‑san roam the house hunting insects to eliminate. While Hoi Hoi‑san focuses on pests, Combat‑san is also eager to take down the rival robot.