2012–2015: Early career Okada joined AKB48 in 2012 as part of the 14th generation trainees, after failing to pass the 13th generation audition the previous year. On March 31, 2013, the AKB48 sub-unit was revealed, consisting of the most promising trainee members from AKB48,
SKE48,
NMB48 and
HKT48. The selected members are Okada,
Mako Kojima,
Miki Nishino,
Ryoha Kitagawa,
Nagisa Shibuya,
Meru Tashima and
Mio Tomonaga; Okada, Kojima, and Nishino, the three AKB48 members of the unit, also became known as the The Three Musketeers were later promoted to Team 4 in August 2013, during the third day of the group's
Tokyo Dome concert. On January 29, 2014, Okada and fellow Kanagawa native members
Ryoka Oshima and
Rina Kawaei formed "Team Kanagawa" to promote the new trains in the Yokohama Line. Later in May, she was selected to sing AKB48's 36th single title track "
Labrador Retriever". In the sixth
AKB48 Group general election to determine the lineup for their 37th single, Okada ranked for the first time in 51st place, becoming part of Future Girls which performed the song "Seikaku ga Warui Onna no Ko" in the single "
Kokoro no Placard". In September, Okada was part of the cast for the AKB48 stage adaptation of the manga ''
AKB49: Ren'ai Kinshi Jōrei'', playing Haruko Mizuno. In the group's fifth
Janken Tournament, she placed 14th and appeared in the B-side of the winner
Miyuki Watanabe's solo single. For the group's 38th single "
Kibouteki Refrain", Okada was not selected to sing the title track, but was assigned as one of the centers (lead performers) along with
Nagisa Sakaguchi for one of the B-sides, "Ima, Happy". In June 2015, Okada placed 29th in the seventh AKB48 Group general election.
2016–2019: Rise to prominence, appointed STU48 captain On May 28, 2016, Okada went on hiatus due to poor health. She returned three weeks later, a day before the 8th AKB48 Group general election in which she placed 14th, thus entering the elected
Senbatsu for the first time. In her acceptance speech, she revealed that her hiatus was due to
functional hypoglycemia and that she had considered leaving the group. This was later elaborated in her solo documentary, aired in November on
TBS as the fourth episode of the series titled Since then, Okada has become part of AKB48's main lineup and performed in all the title tracks of their singles, as well as her first solo song "Coin Toss" in the AKB48 album
Thumbnail (2017). On February 22, 2017, Okada announced that she would be holding a concurrent position in the new sister group
STU48 and serve as the group's captain; she would later cite this appointment as what solidified her decision to continue in the entertainment industry. In July, Okada placed ninth in the 9th AKB48 Group general election. On January 16, 2018, Okada held her first solo concert at
Tokyo Dome City Hall, billed "Nana Okada Solo Concert: My Precious Things", in which she performed 23 songs. She also released her first photobook, titled
Kazaranai Hoseki and photographed in
Hawaii, on February 27, and became the center (lead performer) of an AKB48 title track for the first time in the 56th single "
Jabaja", released on March 14. who seeks to start a war between two rival schools and was partly inspired by the Roman emperor
Nero. She later portrayed main character Shozo Hirono in an all-female stage adaptation of
Battles Without Honor and Humanity directed by
Shutaro Oku, titled ''Battles Without Honor and Humanity ~Women's Battle to the Death~'' (2019) and performed at the
Hakata-za in
Fukuoka in a collaboration to commemorate the theater's twentieth anniversary. In June 2018, Okada placed fifth in the tenth AKB48 Group general election with 75,067 votes, thus becoming a
Kami 7. In her acceptance speech, she encouraged the idol
otakus to take pride in their support of AKB48 Group. It would be the last general election held by the group. Okada underwent surgery for
vocal cord nodules in August and was unable to speak for some time while recovering. In December, the AKB48 Group held its first spanning all six Japan-based groups. Okada earned the highest score in the qualification round, in which 155 members participated, and placed third in the finals. In the second event held in October 2019, she placed first again in the qualification round, but did not place within the top three in the finals. STU48's second single "
Kaze wo Matsu", released in February 2019, would include , the first and only STU48 song with Okada as solo lead singer. On July 27, Okada took part in AKB48's first ever live performance in
Malaysia, which was part of the Japan Expo Malaysia 2019 at
Pavilion Kuala Lumpur.
2020–2023: YouTube channels, solo activities, departure from STU48 and AKB48 Okada stepped down as STU48 captain on January 18, 2020 and continued as a regular member until she officially left the group in March 2022, after her final single participation in "
Hetaretachi yo" (2021). Her farewell concert, billed was held at the
Kobe Kokusai Hall on March 18. During her time with the group, Okada had also taken on her first stage producer role for STU48's second original stage
set list, titled
Bokutachi no Koi no Yokan. Okada and fellow AKB48 members Yuiri Murayama, Shinobu Mogi, and
Mion Mukaichi launched their joint
YouTube channel, the , on January 21, 2020. The next day, Okada and Murayama, together known as , performed in a duo concert billed "YuuNaa Independent Concert ~Irreplaceable Time~" at the
Tokyo Dome City Hall. Several AKB48 members participated as guest performers, including Mogi, Mukaichi, and former Team 4 captain
Minami Minegishi, and the rock band
Gacharic Spin served as
backup band. Backstage reporting of the concert by Mogi and Mukaichi was released on the YouTube channel. Okada took third place in the 3rd AKB48 Group No. 1 Singing Ability Competition in December 2020 and joined the vocal group consisting of the event's top nine finalists, later named Nona Diamonds and represented by the agency . In AKB48's 58th single "
Nemohamo Rumor" (2021), Okada was appointed title song center for the second time after "Jabaja". She reprised her role as Nero in the stage play
Majimuri Gakuen: Loudness (2021), where in contrast to previous installments of the
Gakuen series, Nero calls for peace between the opposing factions in the end; idol journalist Hana Inukai connected this to AKB48's recent trend of reducing internal rivalry to present a united front. and was rewarded with her second solo song, "Kowasanakucha Ikenai Mono", which was released as part of AKB48's 59th single "
Motokaredesu" (2022). The song is a
rock ballad and the music video depicted her as a "fallen angel" singing on a building rooftop against a cityscape. In July 2021, Okada launched her individual YouTube channel and announced that she has joined the
Avex Asunaro talent agency with the goal of expanding her solo activities. These include appearances in the television drama
Stolen Love, High School Teacher (2021) and a stage play adaptation of
Magi (2022). with an additional performance scheduled for July 10 at the
Kanagawa Kenmin Hall, which would also be livestreamed. During the concert, she performed the first song for which she wrote all the lyrics, titled "Kono Yo Kara Boku Dake ga Kieru Koto ga Dekitara". She had previously contributed lyrics for BNK48 and its sister group
CGM48, based in
Chiang Mai. Following reports published by
Shūkan Bunshun alleging that she and actor
Hiroki Ino were in a relationship, on November 23, 2022, Okada announced that she was leaving AKB48. Her farewell concert took place on April 1, 2023, at the Kanagawa Kenmin Hall, followed by her final performance at the AKB48 Theater in
Akihabara the next day.
2023–present: Solo debut Okada's solo debut album, titled
Asymmetry, was released on November 7, the same day as her twenty-sixth birthday. All the lyrics were written by her, and the Blu-ray bonus content included footage from the "Starting Over" and "Timeless Flag" concerts. On January 1, 2026, Okada announced that she had left Avex Asunaro (now Avex AY Factory) the previous day, stating that she would continue her activities "at her own pace". == Public image ==