Ore wo Kuruwasu Amai Seijaku

From Fuhoe Scans:"You know, there's nothing I haven't managed to make mine until now."Ryouta, who was born into a branch family of the Kuon group, has been working hard everyday despite being tormented by his hidden inferiority complex for the eldest son of the main family, Shizuka. One day, something that Shizuka says makes Ryouta snap, and the feelings he had been bottling up explode, but for some reason, Shizuka then forcibly kisses him. Taken aback, he punches Shizuka with all his might, but Shizuka is smiling happily at the sight of Ryouta shedding his "good boy" mask. After that day, Ryouta's feelings for Shizuka that he thought he had put a lid on when he was a kid start to become impossible to ignore+