Inu x Boku SS(2009)

In search of independence and solitude, the sharp-tongued Ririchiyo Shirakiin moves to the Maison de Ayakashi, an apartment building full of wealthy tenants, which has its own Secret Service. Ririchiyo is eager to be alone, but upon her arrival, she is greeted by Soushi, an SS agent arranged for her by her parents. Ririchiyo tries to turn away, but Soushi's dogged devotion to his new mistress will not be deterred. The threats against the residents of the Maison de Ayakashi are not to be taken lightly, after all. And despite his puppylike demeanor, Soushi is not to be trifled with...

(Source: Yen Press)

Note: Includes 12 extra chapters.