The film's plot follows six high school students who receive mysterious messages asking them to meet in a classroom at midnight, after which they are targeted by a figure wearing a schoolgirl uniform and a rat mask.

Communicating through text written on notebook pages, she declares "Let's start the vengeance", and crosses Kengo's name off.

Though Misato is supportive, the others are reluctant and are repelled by a rat mask Asuka had crafted for the performance.

Inside the school, Ryota and Saki encounter another person in a rat mask, armed with an axe.

On the roof, the figure attacks Misato, and she trips her assailant down the stairs, causing them to land fatally on their own blade.

Black Rat was screened on 5 June 2010 at the Human Trust Cinema Shibuya in Tokyo, Japan.

[4] The screening was accompanied by a stage greeting event, with director Kenta Fukasaku and actors Misaki Yonemura, Hiroya Matsumoto, Rina Saito, Makoto Sakamoto, and Rihoko Shimomiya present.