On May 1, 2020, she announced she had retired from the entertainment industry.
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.
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.
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 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 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. 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".
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. 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 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. "Haha no Kyoukun" was announced to also be digitally released "soon", 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. Okai rested for a week afterwards, which she was expected to recover in time for her birthday live.
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.
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.
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.
Starting on October 4, Okai became the main MC for the TOKYO MX information variety program Bakusou Roke Hunter.
On November 2, Okai was appointed as an ambassador of Keirin Marché, a media company that endorses beginner and experienced cycling races.
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.
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.
On February 5, Okai's family opened up an official YouTube channel. 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.
- 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.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.
- 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.
- Name: Okai Chisato (岡井千聖)
- Nickname: Chissaa (ちっさー), Okai-chan (岡井ちゃん), Chisato (ちさと), Chippe (ちっぺ)
- Birthdate: June 21, 1994
- Birthplace: Tokorozawa, Saitama, Japan
- Blood Type: A
- Height: 152 cm (4 ft 11.8 in)?
- Weight: 42-43 kg
- Western Zodiac: Gemini
- Eastern Zodiac: Dog
- Hello! Project Status:
- 2002-06-30: Member
- 2005-06-11: ℃-ute member
- 2017-06-12: Graduated (℃-ute disbands)
- UP-FRONT GROUP Status:
- Years in ℃-ute: 12 Years
- Official Kaomoji: ﾘ ・一・ﾘ
- ℃-ute Color:
- Blue (2006-2009)
- Green (2009-2017)
- Audition Song: "Country Roads" from the anime movie "Whisper of the Heart"
- Hello! Project Groups:
- Shuffle Units:
- Concert Units:
- Other Groups:
- Main article: Okai Chisato/Discography
- Digital Songs
- [2010.11.27] LOVE Namida Iro (Matsuura Aya cover)
- [2010.12.10] Manatsu no Kousen (Morning Musume cover)
- [2010.12.10] Egao ni Namida ~Thank You! My Dear Firends~ (Matsuura Aya cover)
- [2011.03.29] Furusato (Morning Musume cover)
- [2017.12.08] Oolong Hai no Onna
- Solo Songs
- [2012.02.02] Tokai no Neon ga Odoroku Kurai no Utsukushisa ga Hoshii (都会のネオンが驚くくらいの美しさがほしい; I Want To Be Beautiful Enough To Overshadow the Neon Lights of the City)
- [2012.04.18] Kimi wa Jitensha Watashi wa Densha de Kitaku (君は自転車 私は電車で帰宅; You Ride Your Bicycle, While I Catch the Train To Get Home) (C-ute cover)
- [2013.04.03] Kanashiki Heaven (悲しきヘブン; Sad Heaven) (Okai Part Ver.)
- Original Songs
-  Haha no Kyoukun
Solo Image DVDs
- [2011.02.25] Solo Live 2011 Vol.1 ~Kaisha de Odottemita!~ Live in Heaven (会社で踊ってみた)
- [2011.04.18] Solo Live 2011 Vol.2 ~Hanzomon de Odottemita!!~ (半蔵門で踊ってみた)
- [2013.10.26] Okai Chisato Birthday Event ~last teenage~
- [2014.09.26] ℃-ute Okai Chisato Birthday Event 2014
- [2015.03.26] ℃-ute Suzuki Airi・Okai Chisato FC Event 2015
- [2015.08.27] Cutie Kankousha Fanclub Tour "Okai Chisato Birthday Party" in Nagano
- [2016.xx.xx] ℃-ute Okai Chisato Birthday Event 2016
- [2017.01.26] ℃-ute Suzuki Airi・Okai Chisato FC Event 2016
- [2017.10.26] ℃-ute Okai Chisato・Hagiwara Mai FC Event 2017
- [2018.09.26] Okai Chisato FC Live ① ~Katte ni Hello Pro 20 Shuunen Omedetou! 1998~2006~ -A, Watashi mo Omedetou!-
- [2018.12.27] Okai Chisato FC Live ② ~Katte ni Hello Pro 20 Shuunen Omedetou! 2007-2012~
- [2019.06.26] Okai Chisato FC Live ③ ~Katte ni Hello Pro 20 Shuunen Omedetou! 2013-2018~
- Main article: Okai Chisato/Publications
- [2010.12.22] Chisato
- [2018.10.13] Okai Chisato 2019nen Calendar (岡井千聖 2019年 カレンダー)
-  Koinu Dan no Monogatari (仔犬ダンの物語)
-  Hotaru no Hoshi (ほたるの星)
-  Ousama Game (王様ゲーム) (as Maruoka Kaori)
-  Gomennasai (ゴメンナサイ)
- [2002–2007] Hello! Morning (ハロー! モーニング)
-  ℃-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@)
-  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)
-  ℃-ute no Challenge TV (℃-uteのチャレンジTV)
- [2015–2016] Afro no Hen (アフロの変)
-  Chou Shiritoriaru (超シリトリアル)
- [2018–2019] Bakusou Roke Hunter (爆走ロケハンター)
-  Tokusou Shirei! Aichi Police (特捜指令！アイチ★ポリス) (as Mai)
-  Suugaku♥Joshi Gakuen (数学♥女子学園)
-  34 Choume no Kiseki -HERE'S LOVE- (34丁目の奇跡 -HERE'S LOVE-)
-  Neruko wa ℃-ute
-  Keitai Shosetsuka
-  Atarumo Hakke!?
-  Akuma no Tsubuyaki
-  1974 (Ikunayo) (1974(イクナヨ))
-  Sengoku Jieitai
-  STRONGER (ストロンガー)
-  Theater in The Round (青山円形劇場)
-  Sakura no Hanataba (さくらの花束) as Koyamada Mei (小山田芽以)
- [2010–2012] Okaichan, Neru! (岡井ちゃん、寝る!)
-  Michishige Sayumi no "Mobekimasutte Nani??"
- [2013–2017] Hello! Project Station
- [2014–2016] MUSIC+
- [2015–2016] GREEN ROOM
- [2016–2019] Upcoming
- [2016–2017] Girls Night Out
-  Tokai no Hitorigurashi (都会の一人暮らし) (Radio drama)
- [2016.10] HELLO! DRIVE! (HELLO! DRIVE! -ハロドラ-) (Fridays)
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".
- 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.
|Youngest Member of Tanpopo#
January 2009 – January 2011
- J.P ROOM Profile (archived)
- Twitter (deleted)
- Instagram (deleted)
- Personal Instagram (deleted)
- Official Blog (inactive)
- Okai Family Twitter
- Okai Family YouTube channel (deleted)
- Okai Family Fanclub
- ℃-ute Profile (archived)
- Official ℃-ute Ameba Blog (inactive)
- Official ℃-ute GREE Blog (inactive)