Tera no Tonari ni Oni ga Sumu

https://comic.pixiv.net/works/9965 Aim for the top of the demon world! Your enemy is the strongest monk!? It's the Heian period, a time when demons and monsters roamed the land. Shinren, a monk serving at a temple deep in the mountains, is haunted daily by a young demon named Yamabuki. Yamabuki's goal is to defeat the strong Shinren and ultimately become the top demon. However, it seems Shinren is no ordinary monk...?