Aisaretagari no Surface

Young actor Tatsuru Hiruma finds himself playing a brother to Kei Kasugai, a popular younger actor he has always admired.
To prepare for the role, they live together for the duration of the shoot. However, Kei's true face, which he thought to be innocent and well-mannered is actually the one of a playboy who sleeps with anyone and everyone...!

(Source: Tokyo Mangasha, translated)