The head maid and Iria Akagami's trusted assistant: Rei Handa. Not much is known about her, though it's assumed she's been with Iria for the longest and shares a strong bond with her. Besides that, like the Chiga triplets, Rei has chosen to stay with Iria no matter what.
Rei herself is a calm individual with the polite attitude of a maid. Ii initially believes she may be cold, though that quickly dissipates after having a friendly conversation with her.
While Ii is on his way back to the mainland with Tomo Kunagisa, it's revealed that the Rei attending with him is actually Iria. Iria and Ii reveal that the "Iria" that was around on Wet Crow's Feather Island is actually Rei and that they switched for fun and to see if anyone would notice. Ii guessed this as the actual Rei threw Hikari Chiga under the bus, which wouldn't make sense for Iria to do, along with a few other details.