"That's the funny thing about hope. Nobody else gets to decide if you feel it. That choice belongs to you."

She is the lead singer of Huntr/x, a world known K-Pop idol group who also secretly operate as Demon Hunters to seal the Honmoon and keep Gwi-Ma and his demons out of Earth. Rumi wishes to close the golden honmoon to get rid of her patterns, being inherited from her father who was a demon, making her a demon hybrid. While Rumi is a Hunter who kills Demons for a job, as the film progresses, because of her encounters with Jinu, she begins to grow more affable towards demon lives and understanding that they are souls in torment, hesitating on killing them with Mira having to do it for her and only taking more Demons down when innocent people were in actual danger. Though she does have some outbursts, almost all of them happened in moments of nervousness or panic and aren't meant to be jerkish or rude. While she did tell Celine she "was glad to see [the Honmoon] destroyed", this was only a heating-up period as she immediately left to confront Gwi-Ma afterwards and at the same time understandably disgusted by her adoptive mother's prejudice which made her stubbornly refuse to see demons in another perspective like she (Rumi) does. She passes the admirable standard as the one who arrived to stop Gwi-Ma just in time before he consumed hundreds of souls, including Bobby, Mira, and Zoey and for successfully restoring the Honmoon and defeating Gwi-Ma presumably for good, as well as for being the one who inspired Jinu to finally stand up against the demon lord and redeem himself by sacrificing himself for Rumi, which gave her the necessary boost to take out Gwi-Ma herself. On the day of the Idol Awards, Rumi performed Golden but was caught offguard when Takedown began to play and Mira and Zoey (actually demons in disguise), going against her, causing her to run away and find the real Mira and Zoey and tried to explain her patterns and her deal with Jinu, running away after they raised their weapons at her. She found Jinu and confronted him, and even tried to help him after he revealed the truth about his past. After becoming disillusioned, Rumi went to find Celine and confronted her, giving up her sword and asking her to kill her as to not be a threat. She then rightfully called out Celine for her horrible way of parenting her and for not fully loving her due to her demon side. She showed up in her demon form at the Saja Boys' concert just in time to stop thousands off innocent souls from being taken, confronting Gwi-Ma and saying she'd build a new and stronger Honmoon, beginning to sing "This Is What It Sounds Like", snapping Zoey and Mira out of their trances and allowing the three of them to finally sing together as they fought their way through hordes of demons to reach each other, making amends and fighting Gwi-Ma's forces together. She motivated Jinu to finally redeem himself by sacrificing himself for Rumi, giving her his soul to empower her and her sword. With the combined strength of all their fans' souls, the trio managed to remake the Honmoon and presumably finally defeat Gwi-Ma. Rumi later fulfilled her promise to Mira and Zoey and accompanied them to the bathhouse. She also presumably took care of Derpy and Sussie after Jinu's death, given that they're shown following Huntrix and Zoey wears a sweatshirt with Derpy's face imprinted. It's implied Rumi finally introduced Derpy and Sussie to Mira and Zoey off-screen before heading to the bathhouse.