Fuson na Hana o Aisureba

Summary

Kazuma, the unruly eldest son at a prestigious dry-goods store, dotes on Koutarou, the son of his father's mistress who was welcomed into the main house after the death of the latter's mother. But Koutarou rejected his confession and slipped through his hands. Then Kazuma is suddently attacked by the accomplished and serious second son, Ibuki! How will Kazuma react to his tenacity!?