Menacing Dog's: Another Secret

From Infinity Studios:

When you're the most notorious delinquent at school you have one hell of an image to maintain. The last thing you need is to be seen taking orders from an innocent puppy-eyed girl. But unfortunately for Keiji Sendai, he finds himself in this exact predicament when, Setsuna Yatsusaki, the shyest girl in school (as well as being the biggest klutz) finds out about Keiji's deepest and darkest secret... that he's a hardcore otaku! With her new trump card, Setsuna blackmails Keiji into becoming her slave. But just how long can a weak naive young girl keep such a dangerous young man as her pet dog? Join in on Setsuna's secret as she sets out to "train" a notorious thug in this unorthodox love story.

Note: Was originally serialized in Dengeki Teioh magazine in 2005 as "Kyouhaku Dog’s". This run ended after the magazine became defunct in 2006.
Serialization restarted in 2010 issue of Dengeki G's Festival! Comic under the title "Kyouhaku Dog’s - Another Secret".