It was about two childhood friends, one saved the other from sexual assault by a teacher when they were kids (it's NOT Doukyuusei). They become best friends and experiment with each other, but one of them ends up marrying a woman, and the other ends up working as a drag queen on a bar. They reconnect years later and become a couple. The one that was married had a child and the child starts experimenting with his high-school best friend, but they end up just as friends. At the end, they show the 2 protagonists growing old together and that last scene is one of the characters outliving the other and thinking that they heard him just before joining him in the afterlife. Is one of the most beautiful mangas that I've ever read and I can't even remember the name.