Sangatsu no Phantasia is a musical project built around vocalist Mia, who collaborates with a rotating lineup of composers and illustrators. The group got its start in 2015 and has since become known for creating music featured in anime series like Kiznaiver and Re:Creators. Beyond the music itself, Mia is also a novelist—something that directly influences the project, as several of the unit's songs draw inspiration from her writing.

The core team includes:

- Vocal: Mia (@3_phantasia)

- Composer: Scop (@scopscop)

- Illustrator: Natsu Asami (@72desuyo)

- Composer: n-buna (@nabuna2)

- Composer: Yuuyu (@yuuyu_ssry)

- Composer: 40mp (@40mP)

- Composer: buzz-G (@buzz_g)