Anoko to iikoto (2015)

Ookoshi, a high school student, discovers a secret about his classmate Takita – her appearance isn't what everyone thinks. Worried he'll reveal it, Takita offers him something tempting to keep it quiet. Meanwhile, Ami arranges to meet someone online, anticipating a romantic encounter. However, her older brother intends to take advantage of the situation, but she won't give in unless he completes a specific challenge.