Sua makes her first appearance in Ep5 as Aru’s classmate. She sits next to her and later share bunk beds, along with Mari and Sehui. 

Sua seems to be always drenched in water, despite her apparent dislike for it. She is always chased by the swim club in order to make her join them, but she declines every time. Some speculate that Sua might have drowned in her previous life.

She also has a crush on the Homeroom/History Teacher, claiming to be in love with his nerdy charm. However, when he takes off his glasses, Sua is repulsed by his looks even though he is handsome by human standards. (The monsters at Refund High have different beauty standards)

Medium-High Tone Croaky/Gurgle-y? She also gives me a super high-strung and socially anxious sort of feel. Kinda like Toko Fukawa from Danganronpa? I might add a very soft bubbling sfx whenever she talks who knows. Maybe something like a less clipped Sucy from Little Witch Academia https://youtu.be/MsHTwT_p4X8?t=53s or a lower pitched Froppy from My Hero Academia https://youtu.be/oKmHKCVEmNA?t=09s 

Feel free to experiment with the voice~