There is one quest in this area, Theater Help Wanted!, requested by M.M. The reward is 30 berries, after going through 3 fights. It is a repeatable reward. After the Player finishes the game, M.M. will ask if the team would like to watch his new play, saying yes will start the Credits sequence.
The Theater has a music box that Kabbu can hit with his horn to rotate it. After a few seconds of music a Crystal Berry will pop out of the music box.