H2 is a Japanese baseball-themed manga series written and illustrated by Mitsuru Adachi. It was serialized in Shogakukan's Weekly Shōnen Sunday from July 1992 to November 1999, with its chapters collected in thirty-four tankōbon volumes. It was adapted into a 41-episode anime series and an 11-episode television drama series, H2: Kimi to Ita Hibi, directed by Yukihiko Tsutsumi.

In Japan, Kōshien (甲子園) generally refers to the two annual baseball tournaments played by high schools nationwide culminating at a final showdown at Hanshin Kōshien Stadium in Nishinomiya, Hyogo, Japan. They are organized by the Japan High School Baseball Federation in association with Mainichi Shimbun for the National High School Baseball Invitational Tournament in the spring and Asahi Shimbun for the National High School Baseball Championship in the summer.