Born in Seoul, he spent his youth living in his home country, as well as Japan, the United States, and Canada.

An aspiring pianist, Seo's exposure to hip hop music in his teens led him to pursue the genre.

[2] His father, who worked for the Japanese company Hitachi at the time, was transferred to Tokyo; this resulted in Seo and his family moving to Japan at the age of five.

[2] While exploring his university options, he entered a club and heard "Outta Control" by American rapper 50 Cent, his first experience with hip hop music.

[6][7] Unsatisfied with his given birth name, Seo chose his stage name after the biblical Samuel: "His words became truths and people took them as sacred.

[1] A member of the New Block Babyz and Guereallaz collectives, he released his debut extended play Welcome to My Zone in October of that year.

[9] After a year and a half hiatus, Seo released "New Dress Girl" on September 14, 2015, in precedence of his first full-length album.

[10] Contributing to the songwriting, composing, and arrangement on the record, as well as playing all instruments with the exception of bass, Frameworks was released on October 2.

[5][22] He also incorporates various genres into his work, including R&B, soul, hip hop, funk, electronica, and synthpop.