Filka performs the ceremony.

"The couldn't have worked without you."

Hoshikaeri, roughly translated as Return to the stars, is a ceremony which allows the soul of a person to properly passed on. Though this was only mentioned in the prequel, it had a very important role passing on Soruen's life.

Even though they have have shrines built for them, it is known between the Celestial Warriors that the souls of Hikitsu and Tomite have refused to complete their respective Hoshikaeri ceremonies and are left behind in Hokkan to guard their priestess' Shinzaho. They get to pass on in peace years later, after meeting Miaka Yuuki and seeing that she's worthy of being the Priestess of Suzaku AND using the Shinzaho to summon Suzaku.