The story is about a young girl named Dia with weak bullet powers who is suddenly recruited by a very powerful family to protect one of the three heirs Cid, a bullet user with powers much stronger than hers and a very bad attitude about everything. She moves to his school to do her new job and the story relates how she and Cid change, and all the other complex interactions in a world where bullets are still facing discrimination.
Interesting premise, started off quite solid and really made you want to know more about the characters. But then the storytelling got a very rushed towards the end and not entirely sure what really happened... A lot of things feel unresolved. Pity.