|“||How dare you show disrespect to onee-sama / If you ever offend her, I will cut you to pieces!!||”|
—Yuma Okita, Corpse Party: Another Child 1 (Chapter 4; Yuma)
Yuma is a teenager with long pink hair done in pigtails and pink eyes. She wears the Satsukiyama Academy school uniform consisting of a brown double-breasted jacket, a white sailor shirt with a black trim, and black skirt with knee-length black socks and black loafers.
Yuma is a foul-mouthed and bad-tempered girl, especially towards anyone who is disliked or doesn't show respect to Erina Yuzuki. She listens and obeys to the latter however, and calls her "onee-sama" (お姉様 onē-sama , lit. "highly respected older sister") as a sign of affection, despite not being related by blood.
Corpse Party: Another Child 1
At school, Yuma makes fun of Tamaki's fatherless family and of how she has to work to be able to afford food. On graduation day, she once again makes fun of Tamaki's financial situation, and also reminds her of her date with Yuuma Shindou, pointing out that she's aware of it in the process. Yuma follows Erina's lead in taking part in the Sachiko Ever After ritual, and consequently ends up trapped in Heavenly Host. Her group consists of Erina, Yuuma and herself.
Yuma clashes with Yuuma from the beginning on due to his dismissing attitude towards Erina, after the latter suggested he forgets Tamaki. She only stops hitting Yuuma after Erina tells her to. While wandering the halls, the group finds five skeletons wearing their school's uniform in a classroom, although Yuuma prevents the girls from seeing them by closing the door. Yuma sarcastically remarks that he might have imagined things, but gets annoyed when Erina clings to him in fear. She then asks Yuuma if he believes in spirits, and reveals that Erina and her had tried to summon the spirit of a girl previously.
The group finds an exit room which Yuma goes to explore alone. After realizing that the exit door is closed, she hears a noise in the room. Peering from the corner of a shoe rack, she's shocked to see a girl with a missing eye, a boy and a headless girl messing with a fresh corpse. As Yuma runs out of the room in a panic, Yuuma asks her what she saw inside. Yuma answers that the exit is blocked. However, she then regains her composure and, without mentioning the three children, Yuma adds she saw Tamaki inside instead. Yuuma goes inside the room but Erina is stopped by Yuma when she attempts to follow him. Yuma declares that she can barely hold her bladder anymore and asks Erina to help her find a toilet, as she is too scared to search alone. While doing that, she manages to slip a broken plank in the door's handles in order to trap Yuuma inside the room and without being noticed by Erina. Yuuma is left behind as they search for the toilets. There, Yuma cheers at finally being able to get rid of the guy.
As they return from the toilets, they meet Yuuma in the halls. As Erina asks him why his sleeve is ripped and where Tamaki is, Yuuma answers that he met some ghost children and that the latter was nowhere to be seen. Yuma insincerely tells Yuuma she's glad to see him alive, and sticks her tongue at him when he points out that he's aware of what her plan was.
Yuuma questions Erina about the Sachiko Ever After charm and the ghostly children, but she hesitates. Realizing that Erina doesn't want to tell him about it, Yuma answers in her stead and explains that Heavenly Host was demolished 30 years ago, and that it shouldn't be existing anymore. She also adds that Sachiko Shinozaki was a student at this school and is likely already dead, and that they got all this information from a blog written by a supernatural author of paranormal research. Finally, Yuma points out that the "ever after" part of the charm might as well mean to "die together."
After walking some more, they stumble upon a skeleton wearing their school's uniform, impaled on some debris. Erina recognizes the skeleton's identity when she spots the cell phone with a dolphin charm she offered Miyako for her birthday in the corpse's hand, and breaks down in tears.
The three later find an infirmary and took shelter there. Yuma tries to comfort Erina by pointing out that the corpse couldn't be Miyako's. Miyako performed the charm with them and, as such, couldn't have turned into a skeleton so soon. Erina snaps back, questioning why it was holding her cell phone then. Yuma is shocked when further asks how she can be so calm when their friend might be dead. As they leave Erina to rest in the infirmary, Yuuma says that he's surprised to see her so upset. Yuma answers that Erina is always thinking about her friends, and that she'd be friends with Tamaki too if it wasn't for Yuuma always speaking about the latter.
Yuma asks Yuuma if they could let Erina rest in the infirmary. As he answers that she should rest too and he'll watch over the both of them, Yuma blushes and then snaps that he should go look for an exit instead. Yuuma agrees and leaves the two behind in the infirmary. She falls asleep not long later.
When Yuma wakes up, Erina has already come to. The latter asks where Yuuma was and is shocked to hear that he has gone looking for the exit himself. Erina apologizes to Yuma for yelling at her earlier. With their friendship mended, the girls set out looking for Yuuma. They wander a while on the first floor before Erina finally suggests going upstairs. Despite the fact that the air seemed ominous, they still decided to go up.
Erina and Yuma arrive at an empty classroom. Stepping on the damaged wood floor, Yuma trips and falls over. Erina asks if she is alright, to which she says yes; however, her foot got stuck. Suddenly, the cabinet nearby falls over and crushes Yuma's stuck foot. As Yuma screams in terror, Erina tries to lift the cabinet, but it does not move an inch even though her nails are all torn. Desperate, Erina asks Yuma to wait while she calls for help and runs out of the classroom. Unfortunately, Yuma confronts the two ghosts, whom she saw dissecting a corpse earlier. They taunt her, saying that she could have avoided this event if she had stayed downstairs, and that both her and Erina would die. Angered by their words, Yuma says that she will kill them if they were to even touch Erina, which surprises the ghosts. However, a wicked smile creep on their faces.
Erina later returns to the classroom with Yuuma, but Yuma is nowhere to be found. When she begins searching for her, Yuma suddenly appears behind her. Erina is relieved to see her again, but when she tries talking to her, Yuma's upper body falls down.
- Yuma calling Erina her "onee-sama" may be an allusion to what CORPSE-PARTY ZERO's character, Shiho Hasegawa calls her eldest sister, Kaori Hasegawa.
Corpse Party: Another Child