Cinderella Nine (Japanese: 八月のシンデレラナイン, Hepburn: Hachigatsu no Shinderera Nain, "Cinderella Nine in August") is a free-to-play mobile video game for iOS and Android published by Akatsuki and Kadokawa. It was released in Japan on June 27, 2017. A four-panel comedy spin-off manga series by Bkub Okawa titled Hachi Nai Gaiden: Senryoku Gai! Katato-chan (ハチナイ外伝 戦力外！カタトちゃん) and a novelization titled Hachigatsu no Cinderella Nine ～Before Summer～ (八月のシンデレラナイン ～before summer～) are being serialized on the game's official website. A 4-episode original net animation adaptation of the four-panel manga titled Katato the Animation (カタトTHEアニメーション) was streamed between May and June 2017, and an anime television series adaptation of the original game by TMS Entertainment aired from April 7 to July 7, 2019.

Tsubasa Arihara (有原 翼, Arihara Tsubasa)

Voiced by: Nozomi Nishida^[2]

Tsubasa is a spirited girl who founds the girls' baseball team and seeks to make friends and have them join. She is optimistic and hard to get down. In the anime, she primarily plays shortstop. She bats and throws right-handed and wears number 6.

Ryō Shinonome (東雲 龍, Shinonome Ryō)

Voiced by: Reina Kondō^[2]

An old rival of Tsubasa's. She aims to go pro and at first rejects the team for being largely inexperienced, claiming that Tsubasa is not taking the game seriously by playing with them instead of players of similar skill. In the anime, she primarily plays third base. She bats and throws right-handed and wears number 5.

Yūki Nozaki (野崎 夕姫, Nozaki Yūki)

Voiced by: Saki Minami^[2]

A tall, unsure girl who is at first hesitant to try team sports after turning out to be unsuccessful at basketball and feeling that she let her team down. Yuuki changes her mind and joins the baseball team after seeing how everyone is supportive and refuses to judge one another's failures. In the anime, she is a first baseman and relief pitcher. She bats and throws left-handed and wears number 3.

Tomoe Kawakita (河北 智恵, Kawakita Tomoe)

Voiced by: Honoka Inoue^[2]

Tsubasa's best friend, whom she calls Tomocchi. The sensible Tomoe plays the straight man to Tsubasa's less grounded antics. In the anime, she is the team's back-up infielder and first base coach. She bats and throws right-handed and wears number 10.

Akane Ukita (宇喜多 茜, Ukita Akane)

Voiced by: Yumiri Hanamori^[2]

A shy girl who wears a cat-eared hooded jacket and speaks in the third person. Akane is untalented at baseball, but quickly improves as she tries her best. In the anime, she is the team's back-up outfielder and third base coach. She bats left-handed and throws right-handed and wears number 11.

Waka Suzuki (鈴木 和香, Suzuki Waka)

Voiced by: Yūbi Midorikawa^[3]

A tsundere girl who is talented at observation and baseball strategy, but must be convinced to actually play after being let down in childhood. Her supportive brother is part of a prestigious university baseball team. In the anime, she is the team's catcher. She bats and throws right-handed and wears number 2.

Ayaka Nakano (中野 綾香, Nakano Ayaka)

Voiced by: Yurika Takagi^[4]

A budding reporter who insists on writing stories for the school newspaper, despite the school not actually having one. Peppers "nya" into her speech; the official subtitles change this to cat puns. In the anime, she is the team's center fielder. She bats and throws left-handed and wears number 8.

Yoshimi Iwaki (岩城 良美, Iwaki Yoshimi)

Voiced by: Nanami Yamashita^[4]

An overdramatic, hot-blooded second-year from the cheerleading squad. She's noted for not being able to turn down a request. In the anime, she primarily plays left-field. She bats left-handed and throws right-handed and wears number 7.

Aoi Asada (阿佐田 あおい, Asada Aoi)

Voiced by: Rika Tachibana^[4]

A second-year with little in the way of tact or personal space and a talent for detail. Aoi ends her sentences with the particle "no da" or "nano da." Extremely good at rock, paper, scissors she is initially the team's third baseman, but later moves to second base. She bats and throws right-handed and wears number 4.

Maiko Kurashiki (倉敷 舞子, Kurashiki Maiko)

Voiced by: Yurika Endō (game),^[5] Iori Saeki (anime)^[4]

A quiet second-year girl and Yūki's classmate in elementary school who excels in various sports like dodgeball. She often has run-ins with the police as she leaves her house at night to separate herself from her estranged parents. In the anime, she becomes the team's starting pitcher. When she is not pitching, she plays first base. She bats and throws right-handed and wears number 1.

Kana Tsukumo (九十九 伽奈, Tsukumo Kana)

Voiced by: Haruka Shiraishi^[4]

A member of the student council overseeing the athletic clubs. In the anime, she is the team's starting right-fielder. She bats and throws right-handed and wears number 9.

Maria Hase (初瀬 麻里安, Hase Maria)

Voiced by: Sarara Yashima^[4]

A quiet girl who is occasionally seen interacting with Ayaka and watching the rest of the team from afar.

Shiho Nōmi (能見 志保, Nōmi Shiho)

Voiced by: Mewhan^[6]

An anime-original character; she is the student council president.

Momoko Kakehashi (掛橋 桃子, Kakehashi Momoko)

Voiced by: Eriko Nakamura^[6]

A teacher at Satogahama High School and the team's adviser.