Ichikawa University Third High School (市川大学第三高等高校 Ichikawa Daigaku Daisan Kōtō Gakkō) otherwise known as Sankou is a high school located at West Tokyo. Its baseball team is one of the prestigious teams in the series, having reached the quarterfinals of the 83rd Spring Koshien.
It is considered one of the big three powerhouse schools in West Tokyo along with Seidou and Inashiro.
Ichidai-san is based off of Nihon Daigaku Daisan HS (日本大学第三高等学校) otherwise known as Nichidai-san (日大三), another powerhouse school in Tokyo. Recently, they won the 2011 Natsu Koshien defeating Kōsei Gakuin 11-0. (By the way, the real Nichidai-san did reach the quarterfinals of the 83rd Haru Koshien - in 2011).
Despite losing their talented first year pitcher Amahisa Kousei after the 83rd Spring Koshien, Ichidaisan was still one of the teams favored to win the West Tokyo Regional Tournament to qualify for the 89th Summer Koshien, but lost to dark horse Yakushi High in the third round.
Kousei returned after their loss in the summer and pitched well during the Tokyo Fall Tournament qualifier for the 84th Spring Koshien. Ichidaisan made it to the semifinals and had a rematch against Yakushi High, but were defeated once again.
They defeated Seidou High in the semifinals of the Spring Tokyo Metropolitan Tournament, but lost to Inashiro Industrial in the Final round. However, they will be seeded in the West Tokyo Regional qualifer for the 90th Summer Koshien and participants in the Kanto Tournament.