Subaru Hasegawa is a high school student and member of his school basketball team, but activities were suspended for a year after the team captain was suspected of being a lolicon. Subaru's aunt Mihoshi Takamura is the advisor of the girl's basketball team in the elementary section at Keishin Academy, which comprises five girls: Tomoka Minato, Maho Misawa, Airi Kashii, Hinata Hakamada and Saki Nagatsuka. Mihoshi asks Subaru to be their team coach, and after some slight coercion, Subaru agrees to coach the team for three days. The girls initially greet Subaru wearing maid uniforms and they call him 'master' in an effort to make a good first impression. The girls change into regular gym attire and when they are about to start practicing, Subaru makes a comment about Airi's stature, causing her to become upset and they decide to practice the next day. During cleanup, Subaru notices Tomoka's talent and takes an interest in her ability. After practice the next day, Maho gets annoyed that they cannot improve as fast as she hoped and runs out. Subaru finds a note in his locker telling him to quit coaching the girl's basketball team and the next day, he is approached by a group of elementary school boys before practice.
「お帰りなさいませ、ご主人様！」。七芝高校一年生・長谷川昴は、場違いにして珍妙なあいさつで迎えられていた。場所は私立慧心学園初等部の体育館。彼を待ち構えていたのは、なぜか５人のかわいらしいメイドさん（しかも全員小学生！）だった……。
高校入学と同時に入部したバスケ部が、不祥事により１年間の休部を余儀なくされるという大惨事に巻き込まれた昴。そんな彼は、従妹にして慧心学園の教師を務める美星に、半ば脅されるように頼みこまれ、気が進まないながらも３日という期限付きでコーチを引き受けることになったのだ。個性的で初心者ばかりの部員たちを指導していく中、昴は唯一のバスケ経験者である、湊智花の美しいジャンプシュートに目を奪われる……。
