"FOLK" is a project album series by Humbert Humbert in which they record self-covers of their standard and popular songs, as well as covers of songs across generations and genres from Japanese folk classics to 1990s J-POP, performed without support in a duo format. From this popular series, which has released four works so far, two titles, "FOLK" and "FOLK 2," are released on analog vinyl as initial production limited editions. The first installment, "FOLK," was released in 2016 as a 15th anniversary release and contains a total of 12 tracks including re-recordings of signature songs such as "Onaji Hanashi" and "Kokugo," a self-cover of "Chiisana Bokensha," the ending theme of the popular anime "Konosuba: God's Blessing on This Wonderful World!" which celebrates its 10th anniversary this year, and covers of songs across generations and genres such as "Seikatsu no Gara (Wataru Takada)" and "Sayonara Jinrui (Tama / Yoichiro Yanagihara)." "FOLK 2," released in 2018, contains a total of 12 tracks including original songs such as the then-new popular song "Eien no Yuhi" and "Tora" with a piano arrangement that continues to the present, as well as cover songs such as "Chiisana Koi no Uta (MONGOL800)" and "Hikoki Gumo (Yumi Arai)." Both works have been newly mastered in mono for this analog release. "FOLK 2," originally released in 2018 to commemorate the 20th anniversary of the group's formation, is released on analog for the first time (mono version).