yaoi with dragon

hey guys !
the plot was kinda like this: a boy got lost inside a forest and there he met this dragon guy who isn't actually a real dragon but the pre-stage of it. in order to become a dragon he needs to spend 20 years (I think) with a human and that human needs to say "you are not a dragon". so he kinda adopts the boy and spends many years with him inside the forest in return the boy promised him he will turn him into a dragon after 20 (10?) years. instead after the years passed the boy breaks the promise and refuses to say the words because he fell in love with the dragon. the dragon then gets mad and vanishes or something and the little boy returns to the village and from then on hunts the dragon. after a long time he finally catches the dragon and so on...I think for the people who knows this yaoi this will be enough info haha