Yuko Oshima

Oshima was born in Yokohama, and was raised in Mibu, Tochigi Prefecture.^[3] Her mother is from Hokkaido. Oshima is 3/4 Japanese and 1/4 American. Her parents divorced 6 months after her family moved to Mibu. Oshima lived with her father while she only saw her mother once after the divorce.^[4] In 1996, she signed as a child actor with Central Kodomo Gekidan. In 2005, she began working as a junior idol in a short-lived idol project Doll's Vox, which was produced by The Alfee vocalist Toshihiko Takamizawa. In 2006, at the AKB48's second audition to form Team K, she was selected out of a pool of 12,000 applicants to join the team. In April, she began working full-time with the group, which debuted with the single, "Aitakatta", in October 2006.^{[citation needed]}

On August 24, 2012, AKB48 announced a reorganization of the teams, and appointed Oshima to be the captain of Team K.^[5]

On December 31, 2013, Oshima announced on Kohaku Uta Gassen that she would be leaving the group.^[6] On February 26, 2014, the last single for her as a member of AKB48 and as the center performer of that, "Mae shika Mukanee" was released.^[7] She graduated from AKB48 on June 9, 2014, by the performance at the AKB48 theatre.^[8]

On July 29, 2021, Oshima married actor and Scarlet co-star Kento Hayashi.^[9] She gave birth to their first child on January 5, 2023.^[10]

Oshima has placed in the top two in the first five AKB48 general elections. In 2009 she placed second overall, losing only to Atsuko Maeda. In 2010, she received the most votes and became the center performer in the single "Heavy Rotation".^[11] In the 2011 general election, she placed second to Maeda once again. In the 2012 general election, she placed first with 108,837 votes and became the center performer in the single "Gingham Check". In the 2013 general election, she was voted second overall with 136,503 votes and lost to Rino Sashihara with 150,570 votes.

Team K 1st Stage Party ga Hajimaru yo (PARTYが始まるよ)

• "Skirt, Hirari" (スカートひらり)

Team K 2nd Stage Seishun Girls (青春ガールズ)

• "Kinjirareta Futari" (禁じられた二人)
• "Fusidara na Natsu" (ふしだらな夏)

Team K 3rd Stage Nōnai Paradise (脳内パラダイス)

• "Nakinagara Hohoende" (泣きながら微笑んで) (Solo Unit)

Himawarigumi 1st Stage Boku no Taiyō (僕の太陽)

• "Boku to Juliet to Jet Coaster" (僕とジュリエットとジェットコースター)

Himawarigumi 2nd Stage Yume o Shinaseru Wake ni Ikanai (夢を死なせるわけにいかない)

• "Confession"

Team K 4th Stage Saishū Bell ga Naru (最終ベルが鳴る)

• "Gomen ne Jewel" (ごめんねジュエル)

Team K 5th Stage Sakaagari (逆上がり)

• "End Roll"

Team K 6th Stage Reset

• "Kokoro no Hashi no Sofa" (心の端のソファー)

Team K Waiting Stage

• "Glory Days"
• "Higurashi no Koi" (new units)