Little Busters! is a Japanese visual novel developed by Key. The story follows the life of Riki Naoe, a high school student who has been a member of a group of friends named the Little Busters since childhood. Riki brings multiple girls at his school into the Little Busters to have enough people to play a baseball game. The game is rated for all ages in Japan, but a version containing adult content named Little Busters! Ecstasy exists as well.

Riki was a child when his parents died, leaving him hopeless and depressed. What saved him was a group of four kids calling themselves the Little Busters. They took Riki out and played with him during his time of need. He really enjoyed being together 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 a baseball practice game and a duel battle system.