I don't know if it's a one shot or what but it goes like this. A little kid is in long with his teenage neighbor and vice versa but he later finds out that his neighbor has a deadly illness that has no cure so he is going to be frozen until the cure is found in the future. They have sex on his last night alive and some years later in the future the neighbor is awakened and cured. It turns out the little boy is the one who made the cure and they end up together. Anyone know this title? Please.

Somehow reminds me of Itsuka Koi ga Kanau Made by CJ Michalski, but there's no cure stuff, though..

Sekai wa minikuidesu..shika shi! Yūjō, yūki, tsuyo-sa wa ikinokoranakereba narimasen..Tiruendo!

I am interested in this.

I am quite sure it is Oujisama no Kiss, which also happens to be by CJ Michalski.

It was Oujisama no Kiss! Thank you!