|Alias||Trick or Treatment|
|Previous Affiliation||Thirteen Party, Plus Six|
|Previous Position||Head of the Tenth Floor|
|Abnormality||Superhuman Hair Control|
|Manga Debut||Volume 6, Chapter 44|
|Anime Debut||Episode 6|
|Japanese Voice||Hiro Nakajima|
Yutori Chikuzen (筑前 優鳥, Chikuzen Yutori) is a senior of Class 13 and a former member of the Flask Plan's Plus Six. Her project name is Trick or Treatment (髪々の黄昏, Torikku Oa Torītomento).
Chikuzen is one of the more mysterious members of the Flask Plan, even by the standards of the Plus Six. When introducing herself, she adds "...I think." after her name. Like the other members, she also adds "Let's try and get along." after her introduction. Like the other members of the Plus Six, she is considered a basis for Class -13, having a personality that separated her even from other Abnormals. She speaks with a rural dialect.
Chikuzen has long, dark blue hair that reaches down to the backs of her knees, with two bangs that cover both her eyes. She wears a light purple bandanna with a white diamond-shaped patch on it, as well as a shoulder-less black dress and black boots. Ten years later, Chikuzen wears a vest over a shirt with the sleeves rolled up, with a belt and a pair jeans. Her midriff is exposed with this outfit.
Thirteen Party Arc
The group first appear before Youka Naze and Itami Koga after they kidnap Medaka Kurokami, offering to slow down the Student Council while Oudo Miyakonojou brainwashes her. Afterwards, the group rides the elevator to the first floor. Yunomae introduces herself along with the others. The Plus Six are engaged by the Loser Team so that the Student Council can head down to the lower floors. She immediately captures all of the Loser Team with her hair, accept for Shigusa Takachiho, who escapes thanks to his reflexes. He punches her in the face, though she uses her hair to protect herself. The momentary distraction though does provide Kei Munakata the time to cut the others free. He opens fire, but she is protected along with the rest of the Plus Six by Shoko Kamimine. While Medaka and company prepare to descend to the thirteenth floor, Chikuzen and the others are still fighting the Loser Team. Chikuzen continues to fight Takachiho. Later, she, along with the rest of the Plus Six and the Loser Team, is defeated by Misogi Kumagawa.
Kumagawa Incident Arc
Chikuzen lies defeated as Kumagawa gloats. Following the battle, she is sent to the hospital along with the rest of Kumagawa's victims. Instead of external wounds, those who got pierced through with the giant screws took severe mental damage. On August twenty-second, Chikuzen is among Medaka's former enemies who show up to cheer for her during the President's Battle. She cheers for Medaka with her victory.
Kurokami Medaka's Successor Arc
Bouquet Toss To The Future Arc
Ten years later, Chikuzen is a hairdresser.
Superhuman Physiology: Chikuzen is one of the only members of the Flask Plan who can use the elevator in Hakoniwa Academy's underground facility, along with Myouri Unzen and the other members of the Plus Six.
Superhuman Hair Control: Chikuzen's Abnormality has not yet been fully identified, but she seems to be able to control her long black hair; extending it, curling it, and hardening it by will.
- The kanji for Chikuzen's project name Trick or Treatment can be translated to Götterdämmerung or Ragnarok, the war of the Norse Gods said to bring about the end of the world. The first kanji in the project name is 髪, which means "hair" and can be pronounced kami, which can be the word for God, making the name Twilight of Hair rather than Twilight of the Gods.