Jinzou Mahou Shoujo Waffule ~Pet no You ni Shitsukerarete~

Waffle is an artificial magical girl made basically from a dog using a black magic.
She escaped from the evil organization and worked as a magical girl of justice since then.
For the peace of others and for her dead father who helped her escape from the organization.
However, she got trapped and became captive again.
Days of hard assault started, and with the power of magic and pleasure, her modification gradually progressed.

[From English DLSite]