Sangatsu no Phantasia is a musical unit featuring vocalist Mia and several composers and illustrators. The unit debuted in 2015 before being featured in anime television series such as Kiznaiver and Re:Creators. In addition to producing music, Mia also writes novels, with some of the unit's songs being based on her novels.

Members
- 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)