Apphia Yu, also known by the alias Ayu Sakata, is an American voice actress, ADR director, and writer based in the Dallas-Fort Worth area, closely associated with Funimation Productions. Her entry into voice acting followed a traditional path; after participating in community theater during her youth, she took private voiceover lessons, produced a demo reel, and mailed it to various studios. This led to her being called in for bit parts at Funimation, and after two years, she landed her first named role. Her career in the industry has spanned numerous titles since the late 2000s.

Yu has built an extensive filmography, lending her voice to a wide variety of characters. Among her most prominent roles are Victorique de Blois in Gosick, Rio Nakamura in the Assassination Classroom series, and You Watanabe in Love Live! Sunshine!!. She also voices Rika Furude in the Higurashi: When They Cry – GOU and SOTSU anime, Saiai Kinuhata in A Certain Scientific Railgun and A Certain Magical Index III, and Laki Olietta in Fairy Tail and its sequel, Fairy Tail: 100 Years Quest. Her repertoire further includes roles such as Chihiro Komiya in Shonen Maid, Hinako Nakayama in Kenka Banchou Otome: Girl Beats Boys, Holmy in the Show By Rock!! franchise, and Borr in SSSS.Gridman. She has also voiced characters in popular series like Classroom of the Elite, Myriad Colors Phantom World, and Dr. Stone.

Beyond performance, Yu has taken on significant production roles as an ADR director. She served as an assistant director for the first season and as the ADR director for the second season of Assassination Classroom. Her other directorial credits include The Disastrous Life of Saiki K., Koro Sensei Quest!, Classroom of the Elite, Harukana Receive, The Quintessential Quintuplets, and SSSS.Dynazenon.

Outside of anime, Yu is the founder of sakevisual, a visual novel development group based in Dallas. As the head writer for the studio, she has created several original games, including the award-winning Jisei murder mystery series and the otome romance Backstage Pass. She is also a writer for the webcomic Ties That Bind. In video games, she is known for providing the voice of the Hat Kid in the critically acclaimed platformer A Hat in Time. She is married to fellow voice actor Micah Solusod.