Definitely needs a Smut tag. Various instances of gay sex. It is just a light bar, some times. It leaves out big parts, yes. But we still get many instances of anal or blow jobs being depicted, if only for a few panels. Not mentioning cum shots and facials. Could you have guessed its explicit nature from the cover? Not really. Nudity? Not unlikely. But shower sex in the first chapter? No.
Beyond that, impressive character development in just a few chapters and rather wholesome. Despite the rape-y beginning of the main relationship. But he did need some punishment. Will look out for tags and probably avoid Yaoi even more now. Being thrown into this as my first one was rather extreme.