デキる男 [Dekiru Otoko]

身寄りのない北斗にずっと送金してくれた「足長おじさん」。20歳の誕生日、初めて会った彼は42歳、剛胆でハンサムで、震えるほど見事な超エグゼクティブ！しかも数日前、むりやり北斗からキスを奪った男だった！　男は北斗を「後継者」として育てると宣言。更に身体まで奪われちゃって…！　年齢差22歳　感じる・直撃・オール書き下ろし！

Summary from Mangaupdates :
Sagishima Takehiko, Hokuto's distant benefactor throughout his growing up with foster parents, is a successful executive. When Hokuto turns 20, he appears in his life in person and turns it upside down in order to groom Hokuto as his successor. But is that all he is, a benefactor? Hokuto wonders whether he might not have a secret reason for his kindness to a supposed stranger. But when he finally gets to ask the question he has pondered all his life, the way Sagishima responds is... surprising.