|Nickname|| Chairman/Prez Yumiko (有美子会長)|
|Birthdate||June 29, 1998|
|Current Age||24 Years Old|
|Agency||Seed & Flower|
|Social Networks||Official Blog / SHOWROOM / Instagram|
|Idol Career Info|
|Former Team||2nd Generation|
|Debuted||December 2018 / Keyakizaka46 2nd Generation|
Seki Yumiko was a member of Sakurazaka46's 2nd Generation.
- Her audition SHOWROOM number was #40
- Favorite things: Taking a train or bus while listening to music (especially like a band with a piano), sleeping a lot, seeing idols
- Favorite food: Ramen (specifically Tonkatsu Ramen)
- Favorite manga: One Piece, Hunter x Hunter, and Tokyo Ghoul
- Favorite artist: Kenshi Yonezu
- Keyakizaka46 oshimen: Watanabe Rika
- If she were to compare herself to something, it would be a cup.
- She was a model with the "NEXT MODEL COLLEGE" agency prior to joining Keyakizaka46, and walked for FACo (Fukuoka Asia Collection) Fashion Show.
- She was an avid fan of Keyakizaka before joining and went so frequently to handshake events that she was recognized by members. She also collected photos of her oshimen, Watanabe Rika.
- She never danced before joining Keyakizaka.
- She was a member of the brass band and plays alto saxophone.
- She performed Sekai ni wa Ai Shika Nai during the Sakamichi Joint Auditions.
- She is a fan of the SoftBanks Hawks baseball team.
- She doesn't like smiling with her teeth in photos, but when other members take the photo, her laugh comes out naturally.
- She is called "Chairman/Prez Yumiko" due to her high-class background. On Episode 244 of Keyakitte, Kakenai? she revealed that she randomly received a MacBook Pro and Saxophone as a gift despite it not being her birthday.
- However, the title first emerged from being the de-facto leader of the "We love Yuichan Society" (唯衣ちゃんを愛でる会).
- Her light stick colors used to be white + orange.
- Sakamichi Joint Auditions finalist → Keyakizaka46 2nd Generation → Sakurazaka46 2nd Generation → Graduation
- Passed the Sakamichi Joint Auditions on August 20, 2018
- Joined Keyakizaka46 2nd Generation on December 3, 2018
- Transferred to Sakurazaka46 2nd Generation on October 14, 2020
- Graduated from Sakurazaka46 on April 30, 2023 at the Sakurazaka46 3rd TOUR 2023 (Announcement: December 13, 2022)
- Naze Koi wo Shite Konakattan darou? (Nobody's fault)
- Plastic regret (Nobody's fault)
- Guuzen no Kotae (BAN)
- Microscope (BAN)
- Sakurazaka no Uta (BAN)
- Sonia (Nagaredama)
- Mugon no Uchuu (Nagaredama)
- Boku no Dilemma (Samidare yo)
- I'm in (Samidare yo)
- Koi ga Zetsumetsu Suru Hi (Samidare yo)
- Cool (Sakurazuki)
- Munen (Sakurazuki)
- Tamashii no Liar (Sakurazuki)
- Sono Hi Made (Sakurazuki)
- 10gatsu no Pool ni Tobikonda (Eien Yori Nagai Isshun 〜Ano Koro, Tashika ni Sonzaishita Watashitachi〜)
- Sajin (Eien Yori Nagai Isshun 〜Ano Koro, Tashika ni Sonzaishita Watashitachi〜)