Natsume Yujincho- Natsume's Book of Friends
Natsume Yujincho is a more calming sort of anime.
It has no defined storyline except Natsume doing errands for the youkai even though it should be the other way around.
Music, of course, would be calming as well. But, it's great music.
Characters are the best. Natsume's changing personality, Nyanko-sensei and fellow youkai for the comedy relief, and ...