Saki Izumi is your average day high school student, looking for a part-time job. She gets lucky when her neighbors ask her to babysit and tutor their lovely children: three junior high school boys. Saki is more than happy to take on such an easy task, but what she soon finds out is that nothing in life is easy. These lovely children love a bit too much. Lustful and fearless, they force Saki to be their sexual slave; they tie her up and use her as their toy to practice all sorts of perverted fantasies. However, Saki gradually begins to enjoy this awkward situation more than she should...

Kodomo no Jikan covers the first three volumes of the manga.