Hidehiro Tanimura, second-year high school student. His mother has passed away, his father has become a shut-in, and his little sister is the only one who can soothe his soul... On the surface, life seems to be happy, but behind the scenes, another "monster" has come to his home. She's cute and naughty but obedient to her desires. Hidehiro's life with the extremely dangerous female teacher Saara-sensei has begun...!!