The Shimōsa (しもうさ) is an all-stations train service in Japan operated by the East Japan Railway Company between Kaihimmakuhari in the Chiba Prefecture and Ōmiya in theSaitama Prefecture. The Shimosa looks like the Musashino train because they use the same train stock. However, there are some differences between these two services, the Musashino train goes from Hachioji or Fuchu-hommachi whereas the Shimosa goes from Shin-Narashino or Kaihimmakuhari.

Kaihimmakuhari Station is a passenger railway station located in Mihama-ku, Chiba city, Chiba Prefecture, Japan, operated by the East Japan Railway Company.