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Hello! Project Wiki

Okai Chisato (岡井千聖) is a former Japanese pop singer. She is a former member of the group ℃-ute under Hello! Project. She is also a former member of Mellowquad and Triplet and leader of Team Okai.

On May 1, 2020, she announced she had retired from the entertainment industry.[1]


Okai Chisato, November 2017

Okai Chisato, May 2017

Okai Chisato, March 2017

Okai Chisato, November 2016

Okai Chisato, April 2016

Okai Chisato, October 2015

Okai Chisato, April 2015

Okai Chisato, November 2014

Okai Chisato, July 2014

Okai Chisato, March 2014

Okai Chisato, November 2013

Okai Chisato, September 2013

Okai Chisato, July 2013

Okai Chisato , April 2013

Okai Chisato, February 2013

Okai Chisato, November 2012

Okai Chisato, September 2012

Okai Chisato, April 2012

Okai Chisato, January 2012

Okai Chisato, November 2011

Okai Chisato, September 2011

Okai Chisato, May 2011

Okai Chisato, April 2011

Okai Chisato, February 2011

Okai Chisato, December 2010

Okai Chisato, August 2010

Okai Chisato, April 2010

Okai Chisato, February 2010

Okai Chisato, January 2010

Early Life[]

Okai Chisato was born on June 21, 1994 in Tokorozawa, Saitama, Japan to Okai Ken and Hitomi.


Okai first joined Hello! Project on June 30, 2002 as one of the fifteen children chosen from the Hello! Project Kids auditions.[2]

In 2004 Berryz Koubou was formed, with the intention of rotating the kids throughout the unit.[3] Okai didn't make the original pick, and the idea was eventually dropped.

The remaining kids ended up forming ℃-ute in 2005.[4] The group didn't make its official debut until late in 2006, with their first major label single released in 2007.


She was a member of Little Gatas until she was added to Gatas Brilhantes H.P.. She was also a part of the unit Athena & Robikerottsu consisting of Okai, Niigaki Risa, Mitsui Aika, and Nakajima Saki in 2007. They sang the opening and ending theme song for the anime Robby & Kerobby.


She was put in the revival unit for Tanpopo with Kamei Eri, Mitsui Aika, and Kumai Yurina.


A video of Okai covering the dance for Dance de Bakoon! was uploaded to ℃-ute's Official Youtube Channel. It achieved 100,000 views in 2 days; upon reaching 500,000 views, ℃-ute's new single Aitai Lonely Christmas was released in celebration.

From October 13 to 22, Okai starred in Akuma no Tsubuyaki with the other members of ℃-ute

On November 27, Okai became the first member of ℃-ute to get her own single and a separate listing on iTunes. Before the year ended, she released two more songs on iTunes.


On January 24, Okai released another song on iTunes. The Solo Live 2011 Vol.1 ~Kaisha de Odotte Mita!~ was also released. The CD contains two songs from her iTunes list, while the DVD has singing and dancing of 12 songs.

On July 4, Okai and Ishikawa Rika starred in a mini drama titled "Tokusou Shirei! Aichi Police". Okai also starred in a stage play featuring Nakajima Saki, Miyamoto Karin and Kudo Haruka. titled 1974 Ikunayo.


On April 18, it was announced that Okai, Mano Erina, Yajima Maimi, and Suzuki Airi will star in a new stage play titled Theatre in the Round. The stage play ran from May 15-17.


On March 2, at SATOYAMA e Ikou! ~Forest For Rest~, Okai was announced a member of the new SATOUMI movement unit, Mellowquad, along with ℃-ute member Yajima Maimi and Berryz Koubou members Tokunaga Chinami and Natsuyaki Miyabi.

On April 1, it was announced Okai would have a regular Thursday segment on CBC’s Go Go Smile.


On March 13, it was announced that Okai would be a member of a newly formed SATOYAMA movement unit called Triplet, alongside Kudo Haruka and Takagi Sayuki.

On March 26, it was announced Okai would be a regular on the TV show Haraichi no Kami Appli.

On June 21, Okai celebrated her 20th birthday at a special event called ℃-ute ~Okai Chisato Birthday Event 2014~. The event featured two performances in Tokyo.


On June 20 and 21, Okai celebrated her birthday in a special fan club tour called Cutie Kankousha Fanclub Tour "Okai Chisato Birthday Party" in Nagano.

On July 24, it was announced that Okai Chisato would be a regular on TV Tokyo's Chou Shiritoriaru.[5] The show ran from August 3 to August 24.

On August 13, Chisato appeared on the TV show VS Arashi as part of "Team Saitama".[6]


On May 29, Okai announced that she would undergo surgery for vocal cord nodules after her birthday, and would have limited activities for a short period after the surgery.[7][8]

On June 22, Okai celebrated her 22nd birthday at a fanclub event called ℃-ute Okai Chisato Birthday Event 2016, featuring one performance at Differ Ariake.

On July 7, she announced on her blog that the surgery was successful.[9] However, after consulting her doctor, Okai could only participate as an MC for the first three Hello! Project 2016 SUMMER shows on July 16 and 17, but returned to fully performing for the following concerts.

On August 20, it was announced that ℃-ute would disband next June at Saitama Super Arena.[10][11] Okai said she would like to continue working in variety afterwards.[12]


On May 27, Okai announced on her blog that after ℃-ute disbands in June she wants to focus on appearing on variety TV shows.[13]

She joined M-line club on July 10.[14]

On October 30, Okai performed two new solo songs titled "Oolong Hai no Onna" and "Haha no Kyoukun" for her Hello! Project 20 Shuunen Kinen Zen'yasai ~One by One~ solo live. "Oolong Hai no Onna" was digitally released on December 8.[15] "Haha no Kyoukun" was announced to also be digitally released "soon",[16] but no further details have been revealed since.

On November 10, Okai's profile was added to J.P ROOM.


On February 18 and 21, Okai held the Okai Chisato Solo Live 2018 ~Oolong Hai no Onna~ at COTTON CLUB.

On May 15, she announced that she was hospitalized because of a recurrence of vocal cord nodules and was scheduled for surgery the next day.[17] Okai rested for a week afterwards, which she was expected to recover in time for her birthday live.[18]

On June 21, Okai celebrated her 24th birthday at a fanclub live titled Okai Chisato FC Live ① ~Katte ni Hello Pro 20 Shuunen Omedetou! 1998~2006~ -A, Watashi mo Omedetou!-, which was also held to celebrate Hello! Project's 20th anniversary with fan-requested songs from between 1996 and 2006. Two shows took place at Yamano Hall.[19]

On August 3, Okai performed at TOKYO IDOL FESTIVAL 2018 on the HOT STAGE. In the first part, she covered Buono! songs as the one-shot unit Cattivo! with Kobushi Factory member Hamaura Ayano and Tsubaki Factory member Asakura Kiki. In the second part of the stage, Okai performed ℃-ute songs with idols who love ℃-ute.[20][21]

On September 22, she held the Okai Chisato FC Live ② ~Katte ni Hello Pro 20 Shuunen Omedetou! 2007-2012~ with two shows at Yamano Hall.

On September 23, Okai was appointed with eight other OG and active Hello! Project members from Saitama Prefecture as Host City Special Supporters for Kumagaya during the Rugby World Cup 2019 hosted by Japan.[22][23]

Starting on October 4, Okai became the main MC for the TOKYO MX information variety program Bakusou Roke Hunter.[24]

On November 2, Okai was appointed as an ambassador of Keirin Marché, a media company that endorses beginner and experienced cycling races.[25]


On January 19 and 20, she held the Okai Chisato Fanclub Tour ~Boso de Asa Ii Hanashi~.

On February 11, she held the Okai Chisato FC Live ③ ~Katte ni Hello Pro 20 Shuunen Omedetou! 2013-2018~ with two shows at Yamano Hall.

On April 26, Okai announced that she has decided to take a break from entertainment activities as she has been continuously working for 17 years since she joined Hello! Project Kids, and she wants to take the time to figure out what she wants to do next in life. She does not know how long her hiatus will be and she will not use her blog or SNS while she rests.[26]

On July 6, it was reported that Okai was in an affair with Mitani Ryouki. Mitani, a renowned professional cyclist, was married at the time and a father to four children. The pair allegedly met in late 2017 and began the affair in spring 2018, when Okai was seen at Mitani's races. At the time the news broke, Mitani and his wife were in the middle of divorce proceedings. Mitani's wife is also seeking child support from her husband and monetary compensation from Okai for damages.[27][28]


On February 5, Okai's family opened up an official YouTube channel.[29] It was deleted a few months later without explanation.

On May 1, Okai announced that she had retired from the entertainment industry and ended her contract with J.P ROOM on April 30. In her blog post, she announced that she would be using the experience she obtained so far to devote to her family's work.[1][30][31]

On May 15, her family opened up an official Twitter account and fanclub.[32][33]

Personal Life[]

Main article: Okai Chisato/Family

Okai has 4 sibilings: two younger sisters, Asuna and Mion, and two younger brothers, Tsubasa and Rimu. Asuna is a former member of Hello Pro Egg. Her father runs a small plumbing business. Her grandfather is half American, making her 1/8 American. She is also the aunt of Asuna's two children.[34]

Okai currently owns 3 dogs: Howl, Pants, and Bra. Howl lives in her parent's house while Pants lives with her. She previously owned dogs named Pine and Lipstick, who passed away in 2013 and December 25th, 2017, respectively. She also owns 4 turtles, which includes Elizabeth and Kamedo.

When Okai joined Hello! Project Kids, she was a second year elementary school student.[2] She graduated from high school in March 2013.

Okai most notably gets along with the other ℃-ute members and Tsugunaga Momoko.

  • Chissaa (ちっさー): Official nickname, given her since joining ℃-ute. Used by members and fans.
  • Okai-chan (岡井ちゃん): Official nickname. Used by members and fans.


  • Hobbies: Watching movies, collecting purikura
  • Special Skill: Getting along with anyone
  • Strong Point: Making everyone laugh
  • Weak Point: Fooling around too much
  • Habit: Walking like a crab
  • Favorite Color: Blue, light blue, brown
  • Favorite Flower: Cosmos and sunflower
  • Favorite Movie: The Terminator, Backdraft, Nankyoku Monogatari.
  • Favorite Book: Shonen Magazine.
  • Favorite Word: "Nice"
  • Favorite Season: Summer and winter
  • Favorite Food: Asian pears, kalbi kuk bap, sushi
  • Least Favorite Food: Eggplant
  • Favorite Song: Uwaki na Honey Pie and GET UP! Rapper
  • Charm Point: Eyes
  • Looks Up To: Fujimoto Miki, Sayashi Riho

  • Discography[]

    Main article: Okai Chisato/Discography

    Indie Singles[]


    Digital Songs
    Solo Songs
    Original Songs

    Solo Image DVDs[]

    Live DVDs[]

    Fanclub DVDs[]


    Main article: Okai Chisato/Publications

    Solo Photobooks[]


    • [2018.10.13] Okai Chisato 2019nen Calendar (岡井千聖 2019年 カレンダー)



    TV Programs[]

    • [2002–2007] Hello! Morning (ハロー! モーニング)
    • [2007] ℃-ute has come. ~℃-ute ga Yatte Kita~ (℃-ute has come.~キュートガヤッテキタ~) (2 episodes)
    • [2007–2008] Haromoni@ (ハロモニ@)
    • [2008] Berikyuu! (ベリキュー!)
    • [2008–2009] Yorosen! (よろセン!)
    • [2010–2011] Bijo Gaku (美女学)
    • [2011–2012] Hello Pro! TIME (ハロプロ!TIME)
    • [2012–2013] Hello! SATOYAMA Life (ハロー!SATOYAMAライフ)
    • [2013–2014] GOGO! Smile! (ゴゴスマ)
    • [2014–2017] The Girls Live
    • [2014–2015] Haraichi no Kami Appli (ハライチの神アプリ)
    • [2014] ℃-ute no Challenge TV (℃-uteのチャレンジTV)
    • [2015–2016] Afro no Hen (アフロの変)
    • [2015] Chou Shiritoriaru (超シリトリアル)
    • [2018–2019] Bakusou Roke Hunter (爆走ロケハンター)

    TV Dramas[]

    • [2011] Tokusou Shirei! Aichi Police (特捜指令!アイチ★ポリス) (as Mai)
    • [2012] Suugaku♥Joshi Gakuen (数学♥女子学園)



    Music Videos[]


    • [2013] Tokai no Hitorigurashi (都会の一人暮らし) (Radio drama)
    • [2016.10] HELLO! DRIVE! (HELLO! DRIVE! -ハロドラ-) (Fridays)

    Solo Events[]

    The event took place in June 2008.

    • Ganbacchae! by Morning Musume
    • Ekimae no Dai Happening by Fujimoto Miki

    The event took place in September 2008.

    • Koi no Hana by Abe Natsumi
    • Bishoujo Shinri by ℃-ute

    The event took place in September 2009.

    • Robokiss by W
    • Zutto Suki de Ii Desu ka by Matsuura Aya
    • Big dreams by ℃-ute

    The event took place in November 2009.

    • Bokura no Kagayaki by ℃-ute
    • As ONE by ℃-ute
    • ONLY YOU by Zoku・v-u-den
    • EVERYDAY Zekkouchou! by ℃-ute

    The event took place in April 2010.

    • ONLY YOU by Zoku・v-u-den
    • Watarasebashi by Matsuura Aya
    • Hajimete Kuchibiru wo Kasaneta Yoru by Matsuura Aya
    • Koi no Jubaku by Berryz Koubou

    Rankings & Milestones[]

    • She ranked 4th in a magazine's 2011 "Girls that seem like they'll become big stars in the future".[37]
    • She ranked at #38 in Anikan R Yanyan magazine's May 2013 "Singing idol you like the most".
    • She ranked 9th in mixi's June 2013 Hello! Project Popularity Ranking.


    • She has said Fujimoto Miki is the Hello! Project member she respects the most.
    • Miyamoto Karin thinks that Okai Chisato is the coolest member of Hello! Project.
    • She often played "Mario Kart" with the ℃-ute members.
    • She was the first member of ℃-ute to get her own single and own listing on iTunes.
    • She was the last active member of ℃-ute to release their first photobook.
    • Okai's audition song was "Country Roads" from the anime movie "Whisper of the Heart."
    • She has a scar on the right side of her nose, and she said she got it before joining Hello! Project.
    • She was known as a "tomboy" in the early years of ℃-ute while she had short hair.
    • She was known for being the only member to post dance covers on ℃-ute's YouTube account (ocutechannel).
    • Okai was the first member of ℃-ute to dye her hair brown. She first had it dyed around the time she joined Hello! Project Kids.
    • Okai is scared of ghosts.
    • As of 2010, Okai was the only current member of ℃-ute with type A blood.
    • She was the shortest member in ℃-ute.
    • In Team Okai, she covers Sayashi Riho.
    • Okai and Yajima Maimi were the last remaining Hello! Project members who were still in Gatas Brilhantes H.P. at the time of the team's disbandment.
    • Okai said she wants to appear on lots of variety shows to get people to know her.
    • She has admitted to being in love with fellow member Hagiwara Mai during their first few years in ℃-ute.[38]
    • Three days after turning 20, she tried her first alcoholic drink.
    • She stated that she would like to visit England because she loves castles and other things from the country.

    Honorary Titles[]

    Honorary Titles
    Preceded by
    Niigaki Risa
    Youngest Member of Tanpopo#
    January 2009 – January 2011
    Succeeded by


    1. 1.0 1.1 Okai Chisato. "ファンの皆様へ" (in Japanese). Okai Chisato Official Blog. 2020-05-01.
    2. 2.0 2.1 Hello! Morning. Broadcast Date: 2002-06-30.
    3. Tsunku. "『Berryz工房』(ベリーズこうぼう)誕生について" (in Japanese). Tsunku Official Website. 2003-01-15.
    4. Tsunku. "℃-ute (キュート) に関して" (in Japanese). Tsunku Official Website. 2005-06-11.
    5. http://natalie.mu/owarai/news/154763
    6. "VS嵐♡岡井千聖" (in Japanese). ℃-ute Official Blog. 2015-07-17.
    7. "ご報告です。岡井千聖" (in Japanese). ℃-ute Official Blog. 2016-05-29.
    8. "℃-ute 岡井千聖に関して" (in Japanese). Hello! Project. 2016-05-28.
    9. "報告です! 岡井ちゃん" (in Japanese). ℃-ute Official Blog. 2016-07-07.
    10. "℃-uteに関するお知らせ" (in Japanese). Hello! Project. 2016-08-20.
    11. "Announcement concerning ℃-ute." UP-FRONT LINK. 2016-08-20.
    12. https://twitter.com/dmny1009/status/766659914630467584
    13. "今後について。岡井ちゃん" (in Japanese). ℃-ute Official Blog. 2017-05-27.
    14. "矢島舞美・中島早貴・鈴木愛理・岡井千聖 M-line club 加入のお知らせ" (in Japanese). M-line club. 2017-07-10.
    15. "配信スタート!岡井千聖「ウーロンハイの女」" (in Japanese). UP-FRONT WORKS. 2017-12-08.
    16. "初ソロ曲「ウーロンハイの女」「ハハの教訓」近日配信開始予定!" (in Japanese). J.P ROOM Inc. 2017-11-10.
    17. https://twitter.com/okai_chisato/status/996271715691868160
    18. https://twitter.com/okai_chisato/status/996627312060727296
    19. "★ファンクラブ会員限定イベント★「岡井千聖FCライブ①~ 勝手にハロプロ20周年おめでとう!1998~2006 ~ -あ、私もおめでとう!-」開催決定!" (in Japanese). M-line club official site. 2018-04-05.
    20. "今年も℃-uteの名曲を岡井千聖と℃-ute大好きアイドルたちがTIFで熱演!" (in Japanese). TOKYO IDOL FESTIVAL 2018. 2018-08-01.
    21. "元℃-uteの岡井千聖、TIF2018で浜浦彩乃&浅倉樹々とともにBuono!を再現 「おいしい2人が組んでくれて、逆に申し訳ない」" (in Japanese). Deview. 2018-08-03.
    22. "[1]" (in Japanese). Hello! Project. 2018-09-19.
    23. <"ラグビーワールドカップ2019™開催1年前イベント" (in Japanese). Saitama Prefecture. 2018-09-18.
    24. "メインMC岡井千聖/司会進行安東弘樹 明日スグ行きたくなるスポット見つけます!TOKYO MX『爆走ロケハンター』2018年10月4日(木)26:10放送スタート" (in Japanese). PR TIMES. 2018-10-01.
    25. https://twitter.com/okai_chisato/status/1058224549102149632
    26. "ファンの皆様へ" (in Japanese). Okai Chisato Official Blog. 2019-04-26.
    27. "元℃-ute岡井千聖の“略奪不倫”で競輪賞金王が離婚 家族崩壊で妻は慰謝料請求へ" (in Japanese). Bunshun. 2019-07-06.
    28. "元℃-ute岡井千聖に競輪選手との不倫報道 選手の元妻から慰謝料請求も" (in Japanese). Nifty News. 2019-07-06.
    29. https://www.youtube.com/watch?v=BXW1YzR3ado
    30. "岡井千聖に関するご報告" (in Japanese). J.P ROOM. 2020-05-01.
    31. "岡井千聖、芸能界引退を発表" (in Japanese). ORICON NEWS. 2020-05-01.
    32. https://twitter.com/okaike_tv0515/status/1261220791942709249?s=21
    33. https://twitter.com/okaike_tv0515/status/1261220834544254978?s=21
    34. http://ameblo.jp/c-ute-official/entry-12206555589.html?utm_source=dlvr.it&utm_medium=facebook
    35. "【℃-ute】岡井千聖の身長や彼氏の噂は?かわいい画像も大量にまとめ!に投稿された画像" (in Japanese).
    36. "岡井千聖のカップと彼氏を大公開!!" (in Japanese).
    37. http://chisatointelligenceagency.files.wordpress.com/2011/06/lib396789.jpg
    38. ℃-ute DVD Magazine Vol.34

    External Links[]