Chitose Misawa is a young student who develops romantic feelings for her art teacher, Haruhiko Shimotsuki. Their relationship becomes complicated by Haruhiko's previous involvement with Chitose's older sister, Mariko, as he had been Mariko's boyfriend before becoming involved with her.

Despite the substantial age difference, significant enough that Haruhiko could be old enough to be her father, Chitose pursues a sexual relationship with him, adding further complexity.

Rumors about their affair circulate through the school, causing social complications for both. These rumors intensify when Haruhiko also becomes romantically involved with another female teacher at the school, creating a love triangle. This development strains Chitose's relationship with Haruhiko further, introducing intense emotional conflict.

Chitose's complete character arc, encompassing the challenges of her relationship with Haruhiko, the damaging school rumors, and the revelation of his affair with his colleague, unfolds across the four-episode OVA series originally released as "Natural" and "Natural: Another."