ASHITA NO YAKUSOKU is a 26 page short story by Katsuhiro OTOMO, included in his short stories collection HIGHWAY STAR:
http://www.mangaupdates.com/series.html?id=6930

It's a crime story, revolving around an obscure murder case involving children. This story can be seen as a prequel to OTOMO's masterpiece DOMU.

Here's the raw scans:
http://www2.zshare.ma/xflkk8p46qbz