The second volume of the seinen light novel
The Guardian of my World (
ボクのセカイをまもるヒト) got out June 2006.
Its by the same author of Suzumiya Haruhi light novel:
Tanigawa Nagaru (
谷川流)
Here's the cover it:
Seinen light novel
Serialized in: Dengeki Maoh
Published under the label Dengeki Bunko.