The Bully and The Crybaby(2016)

Ijimekko to Nakimushi-kun

1-3, 6. Ijimekko to Nakimushi-kun (いじめっ子と泣き虫くん, The Bully and The Crybaby)
High school student Kyosuke despises his long-time rival, Eishi Takano, who's done nothing but make him cry since they were kids!! He told Eishi he'd get his revenge some day. However, one day Eishi took him into a toilet stall and started teasing him and making him cry. To make matters worse, Eishi tells him not to cry for anyone else...!?

4-5. Kizuitara Hameraretemashita. (気づいたらハメられてました。, I Was Trapped Before I Knew It.)

(Source: Renta!)