- Birth Name: Fujii Rio (藤井梨央)
- Nickname: Riorio (りおりお), Fujidon (藤丼), Eeyore (イーヨー)
- Date of Birth: March 4, 1999
- Place of Birth: Aichi, Japan
- Blood Type: B
- Height: 150cm
- Specialty: Backflips, gymnastics
- Hobby: Piano, handball
- Favorite Color: Gold, red, yellow
- Looks Up To: Wada Ayaka, Kudo Haruka, Sugaya Risako, Suzuki Kanon, Yajima Maimi
- Hello! Project groups:
Fujii Rio took part in the sub-member S/mileage audition in August 2011 where she became a finalist but was not chosen as one of the winners. She later participated in the 2011 "Morning Musume 10th Generation Genki Jirushi" audition, but yet again did not pass. Her first appearance as a member of Hello! Pro Kenshuusei took place at the "Hello! Pro Kenshuusei Happyoukai ~Haru no Koukai Jitsuryoku Shindan Test~" event on May 5, 2013.
On January 2, 2015 she was revealed to be part of a new eight member group, later named Kobushi Factory. The unit consisted entirely of trainees from Hello! Pro Kenshuusei, including Hirose Ayaka, Nomura Minami, Ogawa Rena, Hamaura Ayano, Taguchi Natsumi, Wada Sakurako, and Inoue Rei.
On May 12, 2017 Rio announced her graduation from both Kobushi Factory and Hello! Project, to take place during the Hello! Project 2017 SUMMER tour as summer vacation ended and the new school semester would begin. Within the announcement she revealed her intention to devote herself to her studies in order to fulfill her old dream of becoming a teacher or a nurse. However, an official notice was posted to the Hello! Project website on July 6, 2017 announcing that Fujii Rio's contract was terminated early due to discovery of a breach in rules and a failure to fix the issue, the company noting that they came to this conclusion after discussions held with her family.
- [2017.02.xx] Greeting ~Fujii Rio・Ogawa Rena~ (Greeting ~藤井梨央・小川麗奈~)
- [2017.03.25] Fujii Rio / Ogawa Rena Mini Photobook "Greeting -Photobook-" (藤井梨央・小川麗奈ミニ写真集「Greeting-Photobook-」) (Fujii Rio, Ogawa Rena)
-  JK Ninja Girls (JKニンジャガールズ)
- TV Programs
- [2015–] The Girls Live
- [2015–] Hello! Station (ハロ！ステ)
- Music Videos
- Her favorite Hello! Project songs are "Yuuwaku no Kyuujitsu" and "Bishoujo Shinri" by °C-ute and "Shin Nippon no Susume!" by ANGERME.
- Wrote in a magazine that her dreams are to do away with the image of idols being stupid through attending University, like Tsugunaga Momoko and Suzuki Airi, and appearing on quiz shows.
- Her favorite sport is handball.
- Said if she wasn't a member of Hello! Project she would attend University with the goal of becoming a Professor.