As her appearance suggests, Shibushi is a violent individual, breaking Kumagawa's arm without hesitation when first introduced, and attacking Hansode Shiranui, when she arrives to their meeting late and still "talks big". She shows no remorse for her actions, and tells Kumagawa that if he doesn't leave the physical fights for her, she will kill him. When discussing where she would like to go for vacation, she chooses a sea of blood. Having suffered the worst as a Minus, Shibushi believes herself capable of doing the worst, and expresses pride in her weakness. She does however refuse to commit murder while still underage, as her sin would become lighter. Shibushi has a strange relationship with fellow Minus Gagamaru Chougasaki; the two have been together for ten years, though Shibushi claims don't match. Instead, Shibushi remains with Chougasaki because she does not want to die. Along with Chougasaki, she is extremely loyal to Kumagawa, believing him an even greater Minus than she is herself. This loyalty remains even after Kumagawa is defeated and reformed. Shibushi has a tendency to promise "not to do it again" after attacking someone.
Shibushi has blonde hair and green eyes. She is very tall and developed for her age. As a transfer student like the rest of Class -13, Shibushi does not wear the uniform of Hakoniwa Academy. Instead, she dresses in a torn, low-cut, dark brown sailor uniform.
At age five, Shibushi wore a dark-colored one piece dress and black socks.
As a child, Shibushi liked peeling off her scabs; she would often fall and hurt herself on purpose in order to make new scabs. Her parents hated this and would hit her for it. She decided to kill them when she turned twenty years old, not because her parents hit her, but because they never hit her hard enough to form any new scabs, which frustrated Shibushi to no end. Later on she joined a children's baseball team, hoping that the rough sport would help her to produce new scabs more easily, where her Minus "Scar Dead" first developed. Her teammates received unexplained injuries which healed unusually slowly. She began to suspect that her being there was the cause of her teammates injuries. She went to Hakoniwa General Hospital, where she first met Chougasaki, but since it wasn't a disease she was released. Rather than fear her power, she reveled in it and continued with little league baseball until she graduated from elementary school as her teammates suffered from their mysterious injuries. Shibushi and Chougasaki met as children; Shibushi was five and Chougasaki was six. The noise from Chougasaki's game was annoying Shibushi, so she told him to turn it off. He apologized, after which Shibushi hit him over the head with a spiked bat. She was confused to see Chougasaki was unharmed, and to find the bench they were sitting on had been damaged instead. Shibushi and Chougasaki were the last Abnormals to come to the hospital Hitomi Hitoyoshi worked at, though they were not brought in until after she had left. The two became famous for destroying the facility without leaving a trace of it behind. According to Hitomi, this was a feat no other Abnormals could have accomplished.
Kumagawa Incident Arc
Shibushi and Chougasaki interrupt Kumagawa's fight with Kuudou Hinokage, breaking both of their senior's arms. After Kumagawa restores himself, the three face Hinokage together. The three put some desks together and get out their food to have an executives' meeting. Shibushi is inspired by Kumagawa, and decides to follow him from the bottom of her heart. When Shiranui arrives, Shibushi attacks her for talking big after showing up late. She is surprised to see Shiranui unharmed. Hearing Shiranui's plan, Shibushi asks if it is alright, as she has a friend in the Student Council. One week later, at the end of the semester, Shibushi and the other students of Class -13 show up with Kumagawa as part of his new Student Council. After Medaka Kurokami declares a Student Council battle with Kumagawa, the students of Class -13 decide on who will fight first. They are surprised that Kumagawa wants to fight in the General Affairs Manager's Battle. On July twenty-fifth, during the General Affairs Manager's Battle, Kumagawa explains the absence of the other Minuses; they have gone to the beach to enjoy their summer holidays. This however is revealed to be a ruse; Shibushi and the other Minuses attack the Student Council during their Devilize Training. Shibushi takes the lead in the attack, explaining the Minuses' philosophy to the Student Council. After Hinokage's declaration to protect the others, Shibushi seriously injures them in annoyance. As an enraged Hinokage attacks, Shibushi decides to get serious as well. After defeating Hinokage, she and the other Minuses leave. The Minuses reconvene; Shibushi asks Kumagawa who his new candidate for Class -13 is. Waiting outside Class -13's classroom, the other Minuses discuss Youka Naze. After Naze decides not to join Class -13, Shibushi confronts her, and reveals they have sent attackers after Koga. In the face of Naze's anger, Shibushi tells her they can fight in the Secretary's Battle.
One week later, on the first of August, the opposing Student Councils meet for the Secretary's Battle. Tokemichi Choujabaru asks Shibushi to choose the match; Shibushi picks the snake, like Kumagawa. Choujabaru announces the Secretary's Battle will be a match to strip the opponent. The group moves to the stage of the battle, a freezer in the school's canteen. Shibushi is is surprised by Kumagawa's offer of Class -13's surrender if she loses. She promises Kumagawa she will not give up, and enters the freezer without hesitation. After Naze steps in, Shibushi attacks her immediately. She is surprised to see Naze has somehow stolen her underwear, but gets kneed in the face; it was Naze's own underwear. Furious, Shibushi pulls out a set of razors. Shibushi is hit with a Naze's improvised mace. She tries to cut the other girl with her razors, but her attacks fails, and Naze retaliates with her needles. Though damaged, Shibushi gloats that Naze still has not figured out her Minus; she uses it to wound Naze once more. Naze rises to fight again, but Shibushi reopens Naze's mental wounds, forcing her to relive her past trauma. Shibushi declares that a mental attack is the best to use against Naze. She kicks the crying girl away, but is caught off guard when Naze cuts the lights. Finding nothing but Naze's clothes when the light returns, Shibushi begins looking for her. Shibushi eventually tracks Naze down by a trail of blood. She moves into attack, but is shocked to discover Naze has created her own Minus, and freezes her arm. Shibushi tries to retaliate with her Scar Dead, only to discover both physical and mental damage are now ineffective. Shibushi begins to panic, but Kumagawa tells her it is okay to lose, so long as she does so in a flashy way. Shibushi uses her fully powered Scar Dead to try and end the match, damaging both the spectators and the building. She is horrified however when Naze neutralizes even this. She begs Naze to turn around, promising to strip herself. Naze does so, and Shibushi rushes her with a shard of ice, only to be defeated (and striped) by a blast of fire. Shibushi is restored by Kumagawa's All Fiction. Chougasaki carries her on his back as the Minuses make to leave.
On August eighth, the opposing Student Councils meet at the academy's botanical garden for the Treasurer's Battle. The nonparticipants watch the battle on several computer screens. Shibushi looks to Medaka after Kumagawa finishes explaining their mutual history at Hakobune Middle School. Shibushi watches the monitors display Kumagawa's breakdown over Emukae. She and Chougasaki run up to Kumagawa, telling him to pull himself together. The two help Kumagawa leave. On August fifteenth, the Student Councils gather for the Vice-President's Battle. The group moves to an under construction building for the Vice-President's Battle, "Dropping Mad Dog". Shibushi is unimpressed by the others' confidence in Hinokage. Watching, Shibushi is the only one not to think Hinokage's victory is assured, remembering the first time she met Chougasaki. After the building collapses, Shibushi explains the exact nature of Chougasaki's Encounter. After the battle ends, Shibushi and Chougasaki are unconcerned as the student body boos them. She is surprised by Kumagawa's arrival. On August twenty-second, the Student Council and Class -13 gather for the final battle. Shibushi and the other members of Class -13 climb onto the rooftop Medaka and Kumagawa are fighting on. Shibushi watches as the battle devolves into a punching fest. When a crowd arrives to cheer for Medaka, Shibushi states they will gather all of Class -13 to cheer for Kumagawa in turn. She is surprised to hear that the crowd are all Medaka's enemies. After the battle ends, Shibushi and Chougasaki approach the fallen Kumagawa. Shibushi takes his hand, and the pair promise to stick with him. Helping him up on their shoulders, the three prepare to leave the academy. They are stopped by Medaka, who offers Kumagawa the position of vice-president.
Kurokami Medaka's Successor Arc
Unknown Shiranui Arc
At the end of the academic year, Shibushi is among the students present at the Hakoniwa Academy graduation ceremony. Listening to Kumagawa's speech, she encourages him in her thoughts. She smiles at the conclusion of Kumagawa's speech.
Bouquet Toss To The Future Arc
Shibushi and Chougasaki await Medaka in the Ghost Babel, to challenge her as part of the 100 Flowers Run. When she comes to them before Kumagawa, the pair ask her to tell him that they fought with the intent to win. Her message to Medaka is a thank you.
Ten years later, Shibushi's and Chougasaki's whereabouts are unknown.
Superhuman Physiology: Shibushi appears to have great physical strength, as she effortless broke one of Kumagawa's arms, and Hitomi claims that it is because of her and Chougasaki's great power that Kumagawa has been able to launch his plans before the rest of Class -13 arrived at the school. Kumagawa considers Shibushi the only member of Class -13 who can be relied upon to win. Shibushi has demonstrated an aptitude with razors, which she holds three of between the fingers of her left hand.
Scar Dead (致死武器, Sukā Deddo): Shibushi's Minus allows her to re-open any wound ever inflicted on someone, no matter how old. This ability extends not only to physical wounds, but to mental wounds as well, allowing her to leave her victims in a state of mental breakdown. Shibushi's Minus cannot be stopped by suppressants, or even her own death.
- Hatred Weapon Bazooka Dead (憎武器 バズーカー・デッド, Nikushibuki Bazūkā Deddo): Shibushi's fully powered Scar Dead, this attack can reopen wounds even at a distance. This ability can also open the wounds of non-living objects such as metal or concrete, which can cause roofs and walls to crumble and collapse due to "wounds" caused in construction.
- When translated from kanji, Scar Dead means Lethal Weapon.