Another repeat freebie in I. J. Parker's Akitada series (on Amazon):
Rashomon Gate
Akitada, a minor official in the Ministry of Justice, toils at his dull career when a former professor begs him to look into a case of blackmail at the Imperial University. He is quickly drawn into a web of gossip and rivalry before being sidetracked by the murder of a young woman belonging to the lower classes and the disappearance of young student’s high-ranking grandfather. He and his faithful servant Tora pursue both cases eagerly, but the body count rises, and danger stalks them. When Akitada loses his heart to a young woman and wins her against all odds, a murderer has marked him as the next victim.