Kanojo ga Senpai ni NTR-reta node, Senpai no Kanojo wo NTR-masu

彼女が先輩にNTRれたので、先輩の彼女をNTRます

Yuu Isshiki, a first-year university student, learns that his girlfriend Karen is having an affair with his senior, Kamokura. He was so devastated that he asked Kamokura's girlfriend and the most beautiful girl on campus, Touko: "Please have sex with me!" If you are the victim of NTR, just return the same treatment back. This is the shocking "revenge" romantic comedy depicting the relationship between the minds and bodies of four college students!! (Source: Kadokawa, translated)