Effective period / Period of releases: 2015

Japanese noise musician that is known for their wild street performances that often end in police involvement.

They own numerous labels, majority of which are repeated renames of the same label. Labels owned by Yuuko Haii in chronological order are: High Concentration Contaminated Water Records, Super-Malevolent Deity Records, Mambo Records (6), Internet, Dragon Records (13). Also co-owns 高濃度汚染水Records with Namasu Yoshihide.

Artist has also gone through several name changes, starting with Yuuko Haii/Haii Yuuko, to Youko Heidy/Heidy Youko, to Yoshitoki Seishin.