Murai no Koi Gaiden: Great Twin Busters

High school freshman Taiga Shibaki is a solitary delinquent who loves playing piano. If someone picks a fight with him, he always takes the bait and is in and out of the hospital repeatedly due to injuries. So of course, his childhood friend and first love, Nene Satou, worries about him. When Taiga is troubled by this clumsy love affair, Murai, a third-year student at Tatebe Academy, appears before him!?

(Source: Gene Line Comics, translated)