Buaisou Bg No Torisetsu summary:

"You have such a lewd face. This is turning me on more than I expected." Takaomi Ichinose, the eldest son of a powerful corporate family, isn't too fond of his cocky young bodyguard, Touya Kurosaki. Tired of being guarded around the clock, Takaomi gives Touya a ""special"" drink and tries to slip away... but Touya, usually so cool and collected, has such a cute reaction that Takaomi can't hold himself back! And why is Touya so fiercely overprotective of his clients? The troubled son of a distinguished family and a dark-skinned, baby-faced, unfriendly young bodyguard, starting with sex and blooming into pure love!