Akuma wa Hohoemu

The second son in a family of beauties, Naruse Shouta, is a world-famous hairstylist and model. He constantly showers affection over Ichii Hisashi, the grim but pure-hearted high school student who lives across the street. Due to his self-imposed "Under 18 is Prohibited" rule, Shouta has been impatiently waiting for Hisashi to grow up. However, none too soon, Hisashi's 18th birthday approaches...

(Source: Blissful Sin)

Included one-shot: Tactics