I don't like keeping Areas empty so here we go...
Sigma Harmonics was first revealed as one of the trademarks registered by Square Enix. The game was developed by Think Garage, which had developed two titles in the Itadaki Street series and Lord of Vermillion. Key members of the development team previously collaborated on Dirge of Cerberus: Final Fantasy VII. The game was produced by Yoshinori Kitase and directed by Hiroki Chiba, respectively the co-director and co-event planner of Chrono Trigger. Chiba was inspired by Shōwa period writers such as Seishi Yokomizo and Rampo Edogawa, and wanted to create a video game with a similar vibe. The game features character designs by Yusaku Nakaaki. Chiba admired Nakaaki's previous illustrations and recommended him to Kitase, stating "not using Nakaaki's drawings would be a horrible waste [even though] there are lots of awesome designers at Square Enix." - wikipedia
I've tried to look over the website. It's very beautiful and Interactive. I just can't read or understand Japanese that well.
Hopefully anyone who has played the game of has better information will post as well.