Suzuki-san wa Tada Shizuka ni Kurashitai

With his father killed for witnessing a crime scene, Jinsuke has to live in secrecy with his mother. But they can't stay safe for long. Their pursuers catch up with them, and leave Jinsuke's mother for dead. Their mysterious neighbor Suzuki hears the gun shot, saves Jinsuke, and gets dragged into a murderous chain of events... On the run with the targeted boy, the solitary female assassin Suzuki discovers the warmth of human relationships for the first time.

(Source: Silent Manga Audition)