Iori Saeki is a Japanese voice actress and singer born on July 22, 1994, in Kanagawa Prefecture, Japan. She is affiliated with the talent agency Swallow and also pursues a singing career under the stage name NU-KO. Her path to voice acting began with music; as a 17-year-old high school student in 2012, she won an audition for the Konami rhythm game series pop'n music and made her professional singing debut with the song Ren'ai Kansoku. For several years, she was primarily active as a singer under the NU-KO name, performing numerous songs for the BEMANI series of music games and serving as the primary vocalist for the children's arcade game Otoca♥d'or.

Saeki had long aspired to be a voice actress, inspired by performers like Megumi Ogata and Nana Mizuki. To pursue this goal, she enrolled in the P's Voice Artist School and joined Swallow in December 2017, officially beginning her voice acting career in 2018. Her debut anime role was a minor part as a maid in Ms. Koizumi Loves Ramen Noodles. A significant early break came later that year when she was chosen to take over two existing roles, Mitsuki Gero in the Onsen Musume project and Maiko Kurashiki in Hachigatsu no Cinderella Nine, following the retirement of voice actress Yurika Endō.

Since her voice acting debut, Saeki has built a substantial career, landing a wide variety of roles across anime, games, and mixed-media projects. She is known for her versatility, playing characters ranging from serious protagonists to comedic and moe-style roles. Her musical background often lends itself to roles in franchises centered on performance and music.

Some of her most prominent and recognizable roles include King Halo in the massively popular Uma Musume Pretty Derby franchise; Vanilla in Nekopara; Ashley in Lapis Re:LiGHTs; Yashiro Chikama in Adachi and Shimamura; and Kei Ayamine in Muv-Luv Alternative. She has also voiced leading characters like Menou in The Executioner and Her Way of Life, Amelia Rose in The Iceblade Sorcerer Shall Rule the World, Pai Kawahigashi in Pon no Michi, and Ciel in The Stunned Hero and the Assassin Princesses. Other notable roles include Kimie "Tampopo" Kamata in ORESUKI: Are you the only one who loves me?, Yuyuko Tanaka in the Shōjo☆Kageki Revue Starlight franchise, Kozue Kasugai in Rebirth, Maiko Kurashiki in Cinderella Nine, and Moe Yanagida in Tokyo Mew Mew New.

Saeki continues to be an active and sought-after talent in the Japanese voice acting industry, consistently taking on new roles in both anime and video games.