BackgroundLittle Busters!' story revolves around the main protagonist Riki Naoe, a young male high school student. When Riki was a child, his parents died, leaving him hopeless and depressed. A group of three young boys and one girl his age saved him who referred to themselves as the Little Busters, a group dedicated to fighting evil and preserving justice. The leader of the group was Kyousuke Natsume who had a younger sister named Rin. The other two members were Masato Inohara and Kengo Miyazawa, who were rivals despite being friends. They took Riki out and played together with him during his time of need, making him the fifth Little Busters member. In time, Riki enjoyed playing with them, and his grief over his parents gradually faded away. When the story begins, Riki and his friends are seemingly in their second year of high school, except for Kyousuke who is in his third year. They still hang out together, and enjoy their school life.
The story opens on Sunday May 13, 2007, and the next day at school, Kyousuke decides that the Little Busters are going to play a baseball game, except they do not have enough members to have a complete team. Kyousuke gives Riki and Rin the task of going around school to find more members to join, preferably girls so as not to leave Rin the lone girl. Riki finds five girls his age willing to help him out. They are: Komari Kamikita, a childish girl who is very clumsy; Haruka Saigusa, a problem child who likes to start uproars for her own enjoyment; Kudryavka Noumi, a one-quarter Japanese girl in the home economics club who is very bad in English; Yuiko Kurugaya, a girl who is given respect from her peers, and has a self-sufficient personality; and Mio Nishizono, a calm girl with a weak body who is always seen holding a parasol when outside. Throughout the game, Riki hangs out with these girls and learns more about them.