Aru Koroshiya no Kanwa

"I'll kill you beautifully."

Towa is a wealthy conglomerate CEO's sole daughter. Fearing for her life after her parents' deaths, she heeds her father's absurd instructions to move into an apartment building exclusively for criminals to protect herself. She moves in as the legendary assassin "Skull" whose face has never been seen. However, as soon as she moves in, she meets the real Skull, Hajime Koga, and suddenly her life is in danger. The apartment has a rule where any kind of crime is forbidden. In short, what happens outside of the apartment is fair game and as soon as she leaves she'll be killed?!

A never-ending game of "hide-and-seek" unfolds between Towa and the real Skull.

(Source: Hakusensha, translated)