SpoilerMinami Suzuhara is the second person to hatch from a Wonder Egg bought by Ai. Minami is very shy and timid. She has no confidence in herself nor her abilities at all, often describing herself as weak and lacking spirit. She is also very submissive due to her abuse at the hands of her gymnastics coach, obeying her without any questions and accepting the abuse without complaint.
SpoilerMinami was in her school's gymnastics club, the coach of which physically and emotionally abused her. Minami's Wonder Killer takes the coach's form, as her abuse was ultimately the cause of Minami's presumed suicide.
(Source: Wonder Egg Priority Fandom Wiki)