It never plays during a fight and it doesn't belong to any character in particular but it is very relaxed and only plays during times of peace. It played at the very end of the cell saga during Gohan's tribute to Goku after he realized his father wasn't coming back.
It is a very relaxed and simple theme. It also played multiple times during Bulma's stay on Namek
It is a very relaxed and simple theme. It also played multiple times during Bulma's stay on Namek