Mystari's manga / #Security Guard(2)

A phantom thief has been creating an uproar, passing through every defense and stealing countless works of art! When he takes a liking to the "maidenhood" a guard sacrifices to him, he leaves without stealing the goods... The guard of a certain art museum is completely taken in by that scheme. Their relationship began with contractual sex but before they know it, the two of them are attracted to each other. However, the thief's younger brother kidnaps the guard to get revenge on his elder brother and a big group gang rapes him-!

Section Chief Mizuguchi is a fussy man. His coworkers can't manage to hate him, but they can see why no one has wanted to marry him yet. However someone is interested in him, and this someone is writing him vaguely threatening notes of a sexual nature. Is it that mysterious security guard with the sharp eyes?