Miina Isurugi (石動美依那, Isurugi Miina) is one of the prisoners in the Haguro Prison. Her inmate number is LB0004. Her "base" is that of an American serial killer and rapist who was known as the "Killer Clown", John Wayne Gacy.
Miina was the eighth inmate to be sentenced to life and sent to the Haguro Prison. However, instead of #8 she received the bracelet #4 instead. When the other prisoners didn't tell her about this matter, Miina asked the guard. She was later informed that the previous owner of the bracelet #8 was murdered. Because the brain was removed from the victim, Miina said that the culprit was suspected to be Sayoko Onigahara. This was later confirmed by Sayoko herself.
From her murder model Miina has advance knowledge and tricks of her large collection of knives. She is able to wield them with perfect precision juggling them like a clown does juggling tricks. She has complete control of them even when there not in her hand, showing a level of telekinesis over them, this is shown during her fight against Aya that she made her knives stop in mid air before throwing them without touching them at all. She can make these blades appear suddenly such as when she did with Chika during her first night of the murder experiments.
Like a clown Miina has many tricks that surprises her opponents always keeping them on her feet. During Chika's first night she catches the girl off guard by quickly handcuffing her to the bars of the nearby window. She uses her cross necklace to choke her opponent to death, twisting the cross around as the chain tightens on their neck. Another time during her fight she pulls a string of her clown costume pushing herself out from underneath Aya who had her pinned, leaving her in her underwear in the process. When the girls were tasked to kill the criminals she made a complete scarecrow of herself making it wear her costume, distracting a criminal into shooting it while Aya sneaked in for the kill. Later that night she used her charm to make a criminal lower his guard down giving her the chance to handcuff him and slowly choke him to death with her necklace. During the cruise when she was about to be killed by a katana slash she made a complete decoy of herself she switched with at the last second, puffing up when it took the hit.
All of this make Miina a killer who treats her kills as a game as she carries a playful and sadistic nature with her, keeping her targets guessing for her next move.