Her Majesty's Dog

From Go! Comi:

Amane Kamori lives in a rural village, isolated from modern society. She is a powerful medium, able to control living creatures and things through the use of its real name. Her main companion is Hyoue, her guardian demon dog, who she powers up through kissing. Forbidden from revealing her identity, she and Hyoue are allowed to move to Tokyo. Together they work to help both the living and the dead deal with various troubles, while also adjusting to high school society. Amane must deal with jealousy from classmates, who don't understand why the handsome Hyoue is so devoted to her, as well as with her own family attempting to force her to come home. The family even attempts to break her bond with Hyoue. Meanwhile, Hyoue devotes himself to his master, while struggling to hide the forbidden feelings he has for her.