In 1941, Kiyoshi Nobutoki visited various parts of Tohoku as a member of the "Tohoku Folk Song Audition Group." This "Audition Group" included approximately 20 members, such as Shinobu Orikuchi, Hisao Tanabe, Zenmaro Toki, Shinpei Nakayama, Shimizu Fujii, and Yoshiaki Machida, in addition to its leader, Kunio Yanagita. According to NHK Min'yo Chosa no Kiroku 1939-1994 (Records of NHK Folk Song Surveys 1939-1994), compiled by the production staff of NHK's Nihon Min'yo Taikan (Compendium of Japanese Folk Songs) (Broadcasting Business Data Information Department, Japan Broadcasting Corporation, 1995), this attempt at folk song research and transcription was planned by the NHK Sendai Central Broadcasting Station, and Tadachika Takeda, a renowned folk song researcher, also accompanied the group as a representative of the broadcasting station. It was around the Taisho to early Showa periods that Yanagita and Orikuchi, members of the "Tohoku Folk Song Audition Group," developed their research on folklore and other related subjects as academic disciplines, and Fujii and Nakayama incorporated many folk songs into their own compositions and arrangements.

Kiyoshi Nobutoki compiled the piano collection Tohoku Min'yoshu (Collection of Tohoku Folk Songs) (20 pieces in total) in 1941, and the choral collection Tohoku Min'yoshu (33 pieces in total) in 1946. In his autograph scores for these works, the notation "Transcribed by Tadachika Takeda" can be found in various places. The folk songs transcribed by the "Tohoku Folk Song Audition Group" were disseminated to the public through radio broadcasts and the publication of Nihon Min'yo Taikan: Tohoku-hen (Compendium of Japanese Folk Songs: Tohoku Volume) (NHK Publishing, 1952). Information regarding the research trip of the "Tohoku Folk Song Audition Group" and the folk songs heard during that time is also documented in Hisao Tanabe's book Zoku Tanabe Hisao Jijoden (Taisho-Showa-hen) (Hisao Tanabe's Autobiography, Continued (Taisho-Showa Volume)), edited by Hideshi Yoshikawa (Hogakusha, 1982).

It should be noted that the piano scores for Nobutoki's Tohoku Min'yoshu have not been published. Regarding Tohoku folk songs, 9 pieces are included in Nobutoki Kiyoshi Gassho Kyokushu (Collection of Choral Works by Kiyoshi Nobutoki) (Shunjusha, 1950), and 29 pieces in Nobutoki Kiyoshi Gassho Kyokushu (Ongaku no Tomo Sha, 1951). Even in his autograph scores, many fragments related to Tohoku folk songs are scattered, and while vocal scores can be confirmed, piano scores are not found. However, a fair copy titled "Piano Shokyoku Tohoku Min'yoshu" (Piano Miniatures: Collection of Tohoku Folk Songs), prepared by the composer's wife, Mii, remains, containing numerous corrections believed to have been made by Kiyoshi Nobutoki himself. This fair copy is housed at the Tokyo University of the Arts Library.

Principal References

• SP On'gen Fukkoku-ban Nobutoki Kiyoshi Sakuhin Shusei (SP Sound Source Reissue: Collected Works of Kiyoshi Nobutoki) CD and commentary (Tokyo: Japan Traditional Culture Foundation, Victor, 2008).
• Kiyoshi Nobutoki Autograph Scores (Tokyo University of the Arts Library Collection).