Born Takeshi Sakuma, KEN THE 390 is a Japanese hip hop artist, rapper, and voice actor. He made his debut as a voice actor in the 2018 Netflix anime series DEVILMAN crybaby, directed by Masaaki Yuasa. In this series, he voiced the character Wamu, a member of a group of delinquents. His involvement in the project went beyond performing a voice role, as he also served as the rap supervisor for the anime. In this capacity, he worked to integrate rap music into the show's soundtrack, collaborating with a team that included fellow hip hop artists YOUNG DAIS, Hanaya, and AFRA.

Beyond his performance in DEVILMAN crybaby, KEN THE 390 has contributed to the voice acting industry through music collaborations. He has a notable creative partnership with the established voice actor Jun Fukuyama. The two artists collaborated on the song Start, which was used as the ending theme for the promotional anime short film Start, created to showcase the city of Machida, Tokyo. KEN THE 390, who was born in Machida, wrote the lyrics for the song, which was produced by Kan Sano. The track features a vocal performance by Fukuyama alongside rapping from KEN THE 390. This collaboration extended to Fukuyama's second album, P.o.P –PERS of Persons-, which includes their joint track Start.

In addition to his on-screen voice work and theme song performances, KEN THE 390 has been involved in creating music for anime-related projects. He participated in the production of music for the multimedia franchise Hypnosis Mic -Division Rap Battle-. His experience as both a performer and a music producer, particularly within the framework of anime that heavily feature music, defines his career as a voice actor and contributor to the industry.