Rafael da Cruz Gonçalves was born on March 24, 1999, in Rio de Janeiro, and grew up in Campo Grande, in the city's West Zone. He started writing at 12, producing short stories and comics. Music came as an extension of that habit: in the middle of the decade he formed the band Sala 31 with school friends. In 2017 he began posting standalone songs on YouTube, with voice, acoustic guitar and animated clips made on his phone, before gathering the material into his first album.

The stage name comes from the Japanese yōkai kamaitachi, a clawed weasel used to explain cuts made by the wind. The image fits the project. Instead of singing about himself, Kamaitachi tells stories, and sorts his catalogue into four families: Darksong, for horror tales; Murdersong, for crime stories; Historysong, for hybrid narratives; and Lovesong, for romances. The sound moves through indie, pop, rock, jazz and blues, but the structure is always that of a short story, with character, conflict and resolution.

Homem Torto, from November 17, 2017, set that format and brought songs that became entry points for listeners, such as 6balas and cabelos arco-íris. The record has 12 tracks on the version available on streaming platforms and a label credit in the artist's own name. On November 24, 2023, Festa widened the repertoire with 11 tracks and guest spots from Maraia Takai on Clarice and the band Lagum on Canoa.

In 2025 the artist revisited his own work on Acústico Kamaitachi, released by ONErpm in three parts, on August 29, September 12 and September 26, with 14 tracks in the full version. The project mixes re-recorded hits and three new songs, with a stated influence from 1990s and 2000s rock. In an interview with Mídia NINJA, he said he had spent years building characters and stopped talking about himself in the process.

The 2026 tour shows the narrative holds up on stage. Kamaitachi plays Teatro Estação Gasômetro in Belém on November 1 and Teatro Manauara in Manaus on November 2, both sold out according to his official website. The latest single, Fantasia Sombria, runs 8 minutes and 42 seconds and points to a longer, less episodic phase.