IOSYS

IOSYS is a Japanese doujin music circle and independent record label known for electronic and pop music, with a strong emphasis on fan-made works based on the Touhou Project. Formed in the early 2000s, it operates as a collective of composers, vocalists, and graphic designers who publish music and multimedia projects for a broad audience.

The group releases numerous albums, often through Comiket and online platforms, featuring Touhou arrangements, original vocal tracks, and collaborations with other artists. Their musical style blends techno, trance, pop, and hip-hop influences, prioritizing energetic rhythms and catchy melodies. In addition to album releases, IOSYS produces music videos, live performances, and other media tied to their songs.

IOSYS gained international attention through online communities, particularly on Nico Nico Douga and YouTube, where many Touhou-related remixes and music videos circulated widely. One of their best-known works is Cirno's Perfect Math Class, a humorous video and song that became a widely recognized internet meme and helped popularize their style outside Japan.

Although closely associated with the Touhou Project community, IOSYS is not officially affiliated with Team Shanghai Alice, the creator of Touhou. The circle has contributed extensively to the fan-produced music and video scene, collaborating with other circles to publish a large catalog of albums and media.

As of the 2020s, IOSYS maintains an active presence in doujin circles, continuing to release music and participate in events, with activities spanning production, distribution, and online engagement.