A teenage boy is arrested for the murder of two young girls. While he is questioned by the Tokyo police, his 15 year-old sister Saori (Mirai Shida) is placed in the custody of police detective Takumi Katsuura (Koichi Sato). Katsuura is not simply tasked with protecting Saori: he is also expected to get her to talk, and to provide incriminating evidence on her brother.

Ryoichi Kimizuka’s Nobody to Watch Over Me, which was Japan’s official entry to the 2009 Academy Awards (it wasn’t shortlisted), is a taut police drama that exposes one of the less attractive aspects of Japanese culture. We often assume law and order is relatively uniform across the developed world, when in fact it can vary considerably. In Japan there is a widespread assumption that if someone is arrested for a crime, then they are almost certainly guilty of it. There is also an enormous prejudice against the accused’s family: if you raised a child who committed a crime, then you are by a certain logic also to blame. The families of those accused of serious crimes are often hounded by the media, verbally abused by random strangers, and placed under the most unwelcome of spotlights precisely at a time when they desperately need privacy and peace. People have been known to commit suicide from the stress and the shame. The police are often required to provide protective services – from both the public and from self-harm.

Nobody to Watch Over Me explores this harsh, high-pressure scenario, from the perspective of both the protector and protectee. It is a solid, well-executed police drama. Its characters are interesting and flawed. The story progresses in fascinating directions. If it has any significant drawback, it is that it tends to neglect one of its plot threads – a journalist trying to get access to Saori by digging up dirt on Katsuura’s past. In the grand scheme of things that’s a minor quibble, since the key threads are sensitively and powerfully handled.

Koichi Sato gives a very strong central performance as Katsuura. His marriage is failing. He is haunted by a horrifying mistake some years ago that cost a child their life. He is supposed to be going on leave, and instead finds himself guarding a traumatised and resentful 15 year-old. Sato’s performance is a relatively quiet one, allowing much of his personality and inner conflict to come out in the silence. His weariness and melancholy makes him a very understated and sympathetic character. Saori is initially a much more difficult character with whom to engage, but that’s visibly intentional. We warm to her as Katsuura does, as time slowly allows her to let her guard down and open up to him. There is a wonderful bond between the two characters that never feels forced, yet continues to grow over the course of the story. Kimizuka’s focus is wisely on the emotional story, not the murder narrative. It provides a strong point of difference to a straight-forward and commercial police drama. The strong characters and straight-forward narrative sustain the viewers’s attention for the two hours’ running time, but the culture and prejudice that underpins it all sticks in the back of the mind for much, much longer.

An earlier version of this review was first published at The Angriest on 18 February 2014.