Park Twins

Recruited to the Yuna Band sometime after finishing middle school by Bustard, they were asked to speak with someone over the phone and keep them occupied for two hours. Bustard promised them compensation in return, but it is not revealed what it was. Supposedly they have psychic abilities.

At one point, after being contacted by John Smith, the twins are confronted by Onyu on the school rooftop. He insistently questions them about Great Bustard, Crow, and Cuckoo. They laugh almost maniacally and continue to say they know nothing. Before walking away, one of them tells Onyu that they're leaving this world that day.

They are later seen sending a message to John Smith saying they've found the hole in space-time and that it's located in the teacher's restroom on the 2nd floor of the school. They talk about finally being able to escape from Bustard, and there is reference to a murder case they were involved with in the past.

Onyu follows them to the restroom where they were waiting for John Smith and a fight ensues. At one point, one of the twins takes the laptop Onyu was carrying, thinking it must be important to him. When she opens it, it explodes and her face catches on fire.

The two twins are later seen on the ground of the bathroom after the fire extinguishers go off. Onyu berates them and stabs one of the sisters after saying he should escape soon. He is then shocked to see one of the twins and a man in a hat and suit in the mirror of the bathroom. Sunah says once again that she is leaving this world, and explains that Sunmi was actually another her from a different timeline. She mocks Onyu by saying that the world she originally came from is the world where Yuna is the happiest, with her parents still alive and where she's dating the class president, except that Onyu is not there. She tells Onyu that he must catch Cuckoo, and that Bustard and Crow may team up. She then leaves with John Smith, now that her physical body in that world is dead.