Kei Tanaka was born on July 10, 1984 in Tokyo, Japan. He was talented in playing basketball since elementary school and was seriously considering a career as a professional basketball player, until giving up the dream due to injury in the last year of the middle school. To have him to look for something new to do, his mother encouraged him to apply for a cast audition for a film. Through this event, he was scouted by his current agency Tristone Entertainment Inc in Japan.His first TV appearance was with the Nintendo video game commercial for "Mario Party3" in 2000. His acting career started rather humble as a supporting cast member of regular or single episode of TV drama series. In 2003, his role as a best friend of the leading character in TV drama "Water Boys" drew attention. He continued next many years playing supporting roles, as well as appearing on TV variety shows that were not relevant to his acting career. By gradually gaining acting experiences and recognition, he won the first leading role in the film Kogoeru kagami (2008), followed by the leading role in the TV drama Kosodate Play (2009). In 2011, he got married with Sakura, an actress he met through the TV drama "Massugu na otoko", and got their first daughter. He continued his career mostly as a supporting actor, and in 2016, he played the leading role Soichi Haruta in Ossan's Love (2016), a single episode TV drama that drew attention. Its TV series Ossan's Love (2018) was created, which turned out to be a smash hit. Soichi Haruta became his signature role, and he continued to play this role in the film Ossan's Love: Love or Dead (2019) and the second season for the TV series "Ossan's Love: in the sky (2019)". He now has a second daughter, and his career is now flourishing with more leading role offers as recently seen in It Is Your Turn (2019) and Mellow (2020).