When Riki was a child his parents died, leaving him hopeless and depressed. What saved him was a group of four young boys who referred to themselves as the Little Busters.
They took Riki out and played together with him during his time of need. He really enjoyed playing with them, and his grief gradually faded away.
Now in his second year of high school they still hang out, fight and live together, and enjoy their school life.
Little Busters! contains several mini-games, including regular fighting and baseball games.