So JAIKO is a real thing that's happening! Here's the special site for Eiko & friends' appearance at M3 this year:
http://www.2b3pon.com/shimamiya/
No previews for the songs yet, but the titles and credits are available:
1. Boffier ～木を植えた男～ (Boffier ~Ki wo Ueta Otoko~)
Composition - Jakob Svanholm
Lyrics & Arrangement - Eiko Shimamiya
2. Kite
Composition - Jakob Svanholm
Lyrics & Arrangement - Eiko Shimamiya
Jakob Svanholm is a Swedish producer. I've Sound Forum member Sekka found out that Eiko had tweeted him about wanting to sing his music; this is probably what started this project.
Here's the conversation for anyone who's interested.
Eiko also composed another song, the title track of Erika Tachibana's single 水霊 （みずたま） (Mizutama), which is sold at the same event and table.