cheerful and pure music, suitable for stage play, the first one is Love is, with clear rhythm, which is perfect for the frolicking scenes you requested, and the songs are clean, which matches well with the lovely characters you said.

I'd like to recommend the second song, Joe Hisaishi's summer, which I think should be regarded as the best of pure music. Moreover, it meets your requirements, has a strong sense of rhythm, and the genre belongs to the fresh category, which is very suitable for the stage play with lovely characters. I suggest you refer to it.

the third pure music, which I like very much, is the kind of song that makes people feel comfortable after listening to it once. Moreover, it meets your requirements.

The fourth song, "Caring Hobbits", the prelude of this song is dull, the rest are very cheerful, and the song itself has an impulse to dance.

Just these four songs, I think these four masterpieces should have what you need.

You can also go to Weixin to find other bedtime music every night. There are many, and there should be something you like.