From Yaoi Is Life:

The father whom he’d thought was dead was actually a Hong Kong mafia boss?!

Iba Takayuki was leading a peaceful life as a high-school student until the men in black suits suddenly showed up for him one day.

Takayuki learns that in return for inheriting a vast fortune, he must take revenge against his father’s killers and battle for succession rights against his stepbrother, Arthur, a young man only slightly older than himself. But one look at Arthur’s gorgeous — and clearly hostile — face, and Takayuki’s heart is lost…

Takayuki meets Jason, an any-problem-can-be-solved-with-a-fist executive officer, and Craig, a cool and collected staff officer. Trusting in their capable guardians, the two stepbrothers will discover love and conflict in each other as they boldly fight for survival in Hong Kong’s dark underworld!