In essence, the mochi balls which are lightly charred are to be dipped into this sweet-savoury brown sauce at the top; the sauce has a thick syrup consistency and will coat the mochi balls. You can't quite taste the char, but it was satisfying chewing on the mochi balls which were coated with the sauce.
This was somewhat novel and very different from the usual desserts that I am used to. Rating 6.6/10 - mostly for the novelty of it.