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Kenichi Yoshii
Kanji 吉井 健一
Romaji Yoshii Ken'ichi
Alias 09 (Zero Nine (ゼロキュー, Zero Kyū?))
Little Nine (キューちゃん, Kyū-chan?)
Biological Information
Species Human
Gender Male
  • 161 cm / 5'3" (age 16)
  • Around 170 cm (age 17)
Hair Color Beige
Eye Color Light Green
Date of Birth April 2nd, 1997
Unique Features Glasses
Biographical Information
Status Alive
Relationship Status Single
  • Unnamed Parents
  • Unnamed Uncle
  • Unnamed Aunt
  • Unnamed Cousin
Former Affiliation CCC
Occupation Engineer
Manga Debut Line 6; Monster
Anime Debut Episode 6; Dogmatic
Japanese VA Shouta Aoi
English VA Bryson Baugus

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Kenichi Yoshii (吉井 健一, Yoshii Ken'ichi?) was a member of the CCC in which he acted under the codename 09 (Zero Nine (ゼロキュー, Zero Kyū?)). Unlike Zero Seven, he worked in the background developing technologies they could use in the field.

During Plan B (The Ikebukuro Incident), he learned that there was an inside plan to have Nanako eliminated, so he left the CCC with her in order to protect her.


Kenichi's parents died in an accident when he was little, so he was therefore taken in by his aunt and uncle. During his school days, Kenichi was a social outcast and didn't fit in, so he stopped going to school and studied at home instead. However, his aunt, uncle, and cousin were not particularly pleased with this, and they stopped getting involved with him. Meanwhile, Kenichi would always be in his room studying or fooling around with a computer his father left behind.

Eventually, he found out he had a talent in hacking, and one day, he broke into the MPD Public Safety Division 5's network and accessed their files. He got caught doing so and thought he was going to get arrested, but Kirio Kikuhara said he wanted to hire him and use him as a hacker for the CCC. Kikuhara, along with Takeshi Makimura was able to convince Kenichi's aunt and uncle, and thereafter, at age 15, Kenichi moved out and became CCC's hacker, developer and engineer.[1]


Kenichi is a teenage boy below average height and build for his age. He has short ear-length, beige-colored hair, the style of which resembles that of a bowl cut. His bangs cover his forehead and frame his face, and he wears rectangular glasses which he wears over his light-green colored eyes.

After the timeskip, he has developed a more mature face, along with a taller and slightly more muscular build; to the point where he is now taller than Nanako, the latter being 168 cm. He also grew his hair out to about shoulder-length and his bangs grew longer as well, framing his face more than before.


Manga Depiction

Kenichi's appearance without his glasses after the three-month timeskip.
09 PTS
Kenichi's initial look after the timeskip.

Anime Depiction

Kenichi's full appearance in the anime.
Closeup of Kenichi.


Kenichi is a highly intelligent boy with an outstanding hacker and engineering abilities. However, he is rather withdrawn and shy, preferring to stay in the background and handle things from the shadow. Compared to his partner Nanako (Zero Seven), he is quite meek, more kind-hearted and easily sympathizes with others. He didn't join the CCC due to hating devils, but because he had a deep admiration for Kikuhara and wanted to be by his side. At the same time, Kenichi is shown to be rather sneaky, secretly taking pictures of Nanako when he was sleeping.

However, it is later seen that Kenichi has gained more self-confidence, as he left his unhealthy habits behind and is able to stand up for himself and the people dear to him. He knows what he wants and what he should do to achieve his goals. As opposed to his former shy self that wasn't so communicative, Kenichi becomes more honest and straightforward, not afraid to speak his mind.


Nanako Tenjo[]

Kenichi has always had a genuine crush on Zero Seven, but he initially didn't have the courage to straightforwardly approach her and would often secretly take pictures of her sleeping and collect them. However, he later decided to put his unhealthy habit of taking pictures of her behind, as he decides to become her real friend and vows to always be by her side. He is very loyal and protective of her, and due to the large amount of time they have spent with each other; they miss one another when they are apart,[2] understand each other like no one else, and can confide anything to the other party.

Although Kenichi is sure of the fact that Nanako doesn't see him as a man, he has confessed that he does really love her, including the fact that she is in love with Kikuhara. Despite Nanako not reciprocating his feelings nor really understanding his romantic affection towards her, Kenichi is supportive and patient of her no matter what, and they are currently almost always seen by each other's side.

Kirio Kikuhara[]

Kenichi has always had a deep admiration for Kikuhara. Ever since he first met him, Kenichi was drawn to him and wanted to work by his side, since Kikuhara had deep faith in his hacker skills when his own family did not particularly like it. Kenichi mentions that it felts as though Kikuhara gave him a "new world" which is why he is a dear and important person to him. He also states that like Nanako, he would have fallen in love with him if he wasn't straight.[1] Despite Kenichi and Kikuhara having betrayed each other and Kikuhara having committed many bad deeds, Kenichi and Nanako have expressed their desire to protect Kikuhara and be there for him.[3]


  • The name Kenichi means "healthy, strong" (健) (ken) and "one" (一) (ichi).
  • Kenichi's surname Yoshii means "lucky, good" (吉) (yoshi) and "well, mine shaft, pit" (井) (i).


  • Kenichi is the youngest member of the CCC, initially being only 16 years old.
  • Kenichi is a late bloomer, which is evidenced by the fact that he hit puberty when he was 17 years old. When his voice was getting deeper and he was getting taller, everyone around him was shocked and constantly commented on it.
  • Kenichi developed the thermography scope Zero Seven used, as well as a GPS tracking system used to track CCC members.



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Characters of the Devils Line Series
Main Cast
Yuuki AnzaiTsukasa TairaJohannes KleemanAkio KanoJuliana LloydTakashi SawazakiToshiro SakakiRyusei Yanagi

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Keio University
Teachers Keiji Ochiai
Students Miwako TodaShouta AkimuraTsukasa Taira
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MPD Public Safety
F Squad Juliana LloydMegumi IshimaruRyusei YanagiTakashi SawazakiYousuke AsamiYuuki Anzai
A Squad Kirio KikuharaYoshiyuki Uno
B Squad Takeshi Makimura
C Squad Masakazu TakimotoNaoya UshioYuu Kagasaki
Others Aya ShinjoKaname Yukimori Kenichi Morisawa Shizuka MachidaTadaya Hiruta

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Active Members Kaname ShiraseKirio KikuharaAkihito KanzakiYuriko Hyuga
Former members Kenichi YoshiiKouhei Nakamura Mayu SumimoriMegumi IshimaruNanako TenjoNaoya UshioRen Murakami Takeshi Makimura

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Research Haruto MinegishiJulius KurtzMasami KomatsuIbuki Takeya Maiko Hashimoto Midori AnzaiMikaze Akimura Shouta AkimuraTamaki Anzai
ONLO Johannes KleemanTadaya HirutaYuuki AnzaiYuuko TamaruKubo
R2PC Kaname ShiraseSusumu Sofue

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Other Characters
Civillians Akio KanoEkaKaori SumimoriKatsuki SumimoriKousuke ChizuMakoto TamaruMana SumimoriMio SumimoriMiho Kaneda Misaki TakenamiSaki SumimoriSayuri Tenjo Shizuku Takenami Toshiro SakakiYasuhiko TakeyaYuzuru Kikuhara
Bar Cross Minami Okino
Bar CALM Kiwako Oe Ryunosuke KatagiriWataru Akase
Meteorology Plus Yuichi UtsumiYuriko Hyuga
Asahi Railways S.S TamiyaYousuke NakamuraYoriko Narumi
Shirase Hospital Akihito KanzakiFeng Jing