Claim: Hyakko, published by Flex Comix, was written by Haruaki Katō.
Evidence: It started serialization on Flex Comix's free web comic FlexComix Blood on July 12, 2006. Hyakko (ヒャッコ, "White Tiger") is a Japanese manga created by Haruaki Katō. 
Flex Comix Haruaki Katō