Directed by Joon-Hwan Jang
Written by Joon-Hwan Jang
AKA: Save the Green Planet
IMDB

This is how Netflix described this movie:

Believing that aliens in human form are systematically destroying the planet and all humankind, Byung-gu sets out to capture an alien leader and force him to confess. Because all the aliens look like humans, Byung-gu makes an educated guess and kidnaps the head of a chemical company. Byung-gu desperately tries to wring the truth from the man before the police close in and aliens destroy the world.

While that description is somewhat apt, it is misleading. That is the description of a farcical and hilarious comedy. This movie is, at best, an extremely dark comedy. I would probably describe it more as a crime story, though.
The main character, Lee Byeong-Gu, believes that aliens are on Earth planning on destroying the planet. He captures the head of a chemical company that he used to work at, and which put his mother in a coma. Clearly this isn't a laughfestival.
This movie is very interesting, regardless of the false pretense that I watched it under. There are torture scenes, but they aren't too intensely graphic.
The very end is kind of silly and expected for a movie like this, but it doesn't really make the happening throughout justifiable or funny. The main character is psychotic and methed up. He spends a lot of the movie torturing a dude in his mannequin workshop. If that sounds hilarious to you, then this is the comedy for you. If you want to see an interesting crime movie, that isn't too dark, but is still fairly dark, then this is where to go. I liked it, but I can't fully recommend it.

7/10