Amai Koe wa Saidai Volume de

Yuuta Mogami, a junior in his high school club, is a handsome and friendly guy. Every single day, he comes onto his upperclassman, Daichi Seto, who goes to a neighboring university, libidinously, saying, "I masturbated to your voice" without giving up despite getting brushed off each time.

Even though Daichi should be fed up with Yuuta, his direct "lovey-dovey attack" throws him off his pace. In the end, when he sees Yuuta chatting happily with his friends, he gets jealous...

(Source: Takeshobo, translated)

Note: Originally released as a one shot titled Eccentric Boy ni Gochuui (エキセントリックボーイにご注意).