Red Velvet, comeback world view. Who is "ATTACK on Titan"?

● 5 people who live in the "mansion" are open from the beginning. Four people and one “ATTACK on Titan” live.

-Currently, very similar characters of Yeri, Wendy and Surgi have been confirmed. JOY is similar to the character by the window.

● In the end, IRENE explains “ATTACK on Titan”.