Title: Shion ~Zankokuna Mahou no Tenshi~
Original title: シオン ～残酷な魔法の天使～
Length: Short (2 - 10 hours)
Year: Japan 2007-04-20, English Patch 2009-06-21
Developer: Lilith Mist
Publishers: Lilith Mist
Language: English
Voice: Japanese
Related Anime: AniDB
Translation: Dark Translations

Description:
Are you still.....a human being?

The girl who adores cosplay appeared before you, but you did not know who she actually was. She was staring mutely at me. Unfriendly at all, though she was wearing funny clothes.
My life was completely changed by the encounter with the beautiful girl Sion who once attempted to * me....

Important:
1. You need to change locale to Japanese.
http://erogedownload.com/faq/changing-to-japanese-locale-on-windows-7/

2. No need to install.

Screenshots: