(Shamelessly copied from Wikipedia)

Wanko to Kurasou follows the life of Yuuichi, a college student, over several months. He teaches a cram school and lives alone. He was an orphan when young, and was adopted by an escort. He spent many years growing up in brothels, and eventually entered the industry himself. The experiences he had when maturing resulted in him becoming cold and cynical towards the themes of love and attachment.
It is set in Japan, in a world parallel to reality, with the exception being that there exist a variety of pets known as Anthropoid animals. These pets include cats, dogs and birds, though birds never make appearances in the game. They have human form (ears and tails seem to be the only outward changes in appearance,) show some intelligence, and are even allowed to hold special jobs. However, they still retain much of their animal instincts, most notably the urge to mate during the Spring and Fall seasons.

I found that this was a pain to find a download for and decided to put it up here. 

To install:
1. set your computer to Japanese locale (http://windows.microsoft.com/en-SG/windows-vista/Change-the-system-locale)
2. Mount the image and install
3. Install the english patch to the directory of the VN itself
4. Start reading