Ore wo Mamoru to Chikatte yo

Heartthrob idol Kanan Shiina ends up helping Mouze Masaomi, a man who collapsed in front of him. Mouze, in a rush of gratefulness, kneels down and requests to "return his gratitude." When Mouze's manly body and back tattoo caught Kanan's eye, he offers Mouze to live with him as his bodyguard to return the favor. A dutiful sense of gratitude and a slut hidden behind a heartthrob facade.

(Source: Kadokawa, translated)