And here's the cover of the light novel
らき☆すた らき☆すた殺人事件
Lucky☆Star Lucky☆Star Satsujin Jiken
Shounen(boy's) light novel
Published under the shounen(boy's) light novel label
Sneaker Bunko.
Author and illustrator: Yoshimizu Kagami
Written and illustrated by the same mangaka of the Lucky Star manga