[NeoSam]

撲殺天使ドクロちゃん
Bokusatsu Tenshi Dokuro-chan

Official anime site:
http://www.bin-kan.com/

Based on a shounen light novel.

Based on a shounen light novel thats published under the shounen(boy's) light novel label Dengeki Bunko.

For now there are 9 volumes released of this light novel.
Here are the covers:

Spoiler:

Genre: Shounen, Fantasy, Comedy