What is this Яой manga?

In this manga, this guy was walking around town after he had a bad experience with this girl and he runs across a little book store. While inside he sees a boy who is about 11 and the boy's father/babysitter. The father/babysitter has to do something for a minute, so he leaves the child.

While the father is gone, the main character comes in. The child places a book down. He warns the guy not to read it, but the guy does anyway. Чтение the book sends him back in time. Apparently he had been reborn several thousands years later as he was back in time with his other self. His other self was a warrior and I believe also the commander of the army.

In the past, the king/prince that he served used him as a sex slave. They were in a desert. He falls in Любовь with the king/prince and tries to save him when he's supposed to die. He returns to the his original time period and is upset that he could not be with the king/prince, only to bump into a guy who looks like the king. I'm not sure exactly how it goes but I do know that both of the ones reborn had gone back in time.