Kōki Mitani is a Japanese playwright, screenwriter, actor and film director and was previously married to Japanese actress Satomi Kobayashi. He was named after Taihō Kōki, the youngest sumo wrestler to become yokozuna. He studied dramatics at Nihon University.

Sherlock Holmes or Puppet Entertainment Sherlock Holmes is a Japanese puppetry television series written by Kōki Mitani and produced and broadcast by NHK. The puppets for the series were designed by Bunta Inoue. The first series of 18 episodes was broadcast on Sundays from 12 October 2014 to 15 February 2015 by NHK Educational TV (ETV); the first six episodes were broadcast by NHK General TV (GTV) in March and August 2014. A special programme was broadcast on 5 October 2014 while a "Sherlock Holmes Award" was broadcast on 28 December 2014. Each episode was rebroadcast on successive Fridays. The programme won the Japan Sherlock Holmes Award on 22 March 2015.