Espionage Code: I'm a Useless Abacus

In 1939 Tianjin, Shen Mancang, a bookkeeper who had been an auditor for ten years in his previous life, transmigrates into the body of a clerk at the puppet Tianjin Municipal Public Security Bureau. He develops the ability to see the accounts of people's hearts—each person's head floats with hidden secrets. Li Fu hangs himself in the warehouse, the black ledger disappears, Japanese spies hide in the foreign firm, and the Kuomintang military intelligence list appears in the pawnshop. As the abacus beads clatter, every entry's debit is a life, and the credit is also a life. Sitting on the beam of the ledger, he balances accounts for the dead and carves out a way to survive for himself. — Description from novelcodex.org