>>150272382
Rumi is the name of the character, and her singing voice was EJAE, who was a failed Kpop trainee turned fairly famous songwriter who got the singing slot by virtue of recording herself singing the demos and the Sony execs going "Well, we don't need to find another vocalist, you're fucking great". There's a bit of an extra bit of irony that an unironic hag, since she's 33, btfo'ed all the existing Kpop groups where the median age is like early twenties at the most.