Azusa is set at a point a few decades in the future where school baseball teams are not only co-ed, but also allow a couple special-purpose "sports robots" for the teams with the money to buy them. The team our protagonists belong to is anything but rich though, and the manager is an old man who thinks sports robots are an abomination to the game anyway. Tired of losing to teams with robots and one player short of a complete team regardless, one of the guys on the team goes to buy a sports robot--but he finds the only kind of robot he can afford is an out-of-date maid robot, from back in the day before a law was passed banning human-looking robots. Azusa, the robot he buys, is still in working order--she's earnest, cute, and determined to do what she can. But while she's great at making the team's clubhouse spotless, when it comes to baseball she has no idea how to play...
From there the team goes to training camp, finally starts to play hard and believe in themselves, Azusa has some surprises up her sleeve