Kairaku no Houteishiki: LEVEL-C

Mizuki is a male fashion model with a nice apartment. Kazuomi just had his girlfriend kick him out. Kazuomi sets out to find someone new to live with and sees Mizuki on the street. Kazuomi thinks Mizuki is cute and asks to stay with him in exchange for great sex. Mizuki thinks he is joking until they are at his apartment later that night and Kazuomi makes good on his promise.
(Source: Anime News Network)