Repentance, Secret Garden (this one is the most classic, and very suitable), Song of the Secret Garden (this is played by the ocarina, very nice), and some of Hisaishi Joe's, such as: Galaxy no. Jun, Castle in the Sky, etc. are all a bit sad, but they mainly embody softness. I would like to recommend another very good one to you: Breeze and Drizzle (this song is extremely pleasant to listen to)