Kizuna Ai is a Japanese virtual YouTuber and musical artist who is widely recognized as the first creator to popularize the virtual YouTuber, or VTuber, concept beginning in December 2016. As a virtual being, she is a character with a defined personality and appearance, and her voice is provided by a human voice actor. In April 2020, it was formally confirmed that the voice actor Nozomi Kasuga has been providing the voice for Kizuna Ai since the character's debut in the autumn of 2016. Kasuga also took on an advisory role at Kizuna Ai Co., Ltd., the company established to manage the character's activities.

Kizuna Ai, credited as herself, has voiced roles in anime television series. Her most prominent role is in the 2023 anime series Kizuna no Allele, an original project based on her virtual persona, where she plays a version of herself. Prior to this leading role, she had cameo voice appearances in other anime, including Ingress and Magical Girl Site. She also performed the theme song for the animated film Laidbackers.

Beyond her anime voice roles, Kizuna Ai has achieved significant recognition as a pioneer of VTuber culture. Her main YouTube channel, A.I.Channel, has amassed over three million subscribers. Her influence has been acknowledged by Newsweek Japan, which listed her among its globally respected Japanese people. After an indefinite hiatus beginning in 2022, she resumed her activities in February 2025 with a renewed focus on her career as a musical artist, aiming to share a new form of J-pop with a worldwide audience.