Sayounara Ryuusei, Konnichiwa Jinsei

Long ago, the most ancient of divine dragons was slain by a human. The mighty dragon accepted its death when suddenly, it was reborn as Dolan, a man who lives in a quiet village. While spending another peaceful day toiling in the fields, he meets Celina, a half-human, half-snake creature looking for a partner. The unlikely duo become friends, but challenges lie ahead that threaten their new bond.

(Source: Cunchyroll)