Silencer

Silencer summary:

(from ebookjapan):
Shizuka Katsuragi is a female detective who loves silencers. She is assigned to the "annex" of the Community Safety Division, a hive of activity in the Tokyo Metropolitan Police Department.
Her partner is Kenya Iha, the most eccentric person in the Metropolitan Police Department. The pairing of the two is a strange one, as they both pull each other down.
With the policy of "conquer poison with poison," her beloved gun quietly blows fire today...