H2
The story is about Hiro Kunimi, Hideo Tachibana, Hikari Amamiya and Haruka. 2 heroes and 2 heroines, thus H2.
At the end of junior high, Hiro was forced to retire from baseball because of the injuries to his arm. So he goes to a high school without a baseball team, and meets Haruka. While Hideo goes to a famous baseball school with his girlfriend Hikari. Soon, Hiro finds out that his doctor didn't have a license, and wrongfully diagnosed him, hot blooded youth baseball manga begins.
Adachi's longest work (34 vols!), his latest baseball story to top Touch. He succeeded beautifully. I try not to write too much about Adachi's works, because anything I might bring up is a whole discussion in itself. There's so many levels (i.e team work, friendship, love, dedications, family relations....) working simultaneously in his works that speech along cannot convey them. Just go and read the mangas.