Gakkou Youkai Kikou: You

This one-shot is basically the prototype for Higanbana no Saku Yoru ni, and is nothing more than a set-up for a story. A girl named Marie Moriya is approached by another girl who calls herself Higanbana, who tells her of a school youkai named meso-meso san. That's pretty much it for this one. It is extremely short, mediocre, and is basically useless. Considering that this came before Higanbana, it hardly qualifies as a complete story. Calling it a one-shot is a bit generous in my opinion, it feels more like someone's first vague idea found in an idea sketchbook. The only nice thing I can say is thatthe art is nice, the concept is nice, and that they later grew this story to its full potential later on. If you are interested in the concept and want to read the full fleshed-out version, then read the manga (or better yet, the visual novel).