It's inappropriate for adults to engage in relationships with children.
Rika is grading papers after class when her student Daisuke starts flirting with her.
Rika doesn't want to hurt Daisuke.
Rika sets Daisuke up with her younger sister.
Rika dates Daisuke.
Daisuke thanks Rika later for introducing him to his new girlfriend.
Rika gets fired form her job after someone discovers her relationship.