Though the space creatures visiting Earth in Before We Vanish can inhabit the bodies of homo sapiens, they don't know what it means to be human. But the more they learn about it, the closer we get to possibly becoming extinct.
Before We Vanish doesn't try to replicate the special effects extravaganzas seen in most alien encounter movies. Instead, it tackles the questions that most films -- and people -- take for granted. The film starts with two big shocks, the first in the form of an elderly couple's gorily dismembered bodies. The second shock is more personal, when Narumi Kase (Masami Nagasawa) learns that her missing husband, Shinji (Ryuhei Matsuda), has been found after a week, but he doesn't seem to know anything about anything. When it seems like Shinji can't remember his infidelity that caused the couple to drift apart, Narumi thinks it's a ploy to avoid angry reprisals from her.
However, it soon becomes apparent that Shinji doesn't know the most basic information about living life. That's because his body is now home to an alien who didn't previously have a physical form. This creature -- along with two others who have been taken over the bodies of a teenage boy and girl -- has been tasked with pulling knowledge from human brains in advance of a mass invasion. So when Shinju touches his finger to the forehead of a design studio exec to harvest the idea of work, all of that meaning leaves the man's brain completely. The hapless exec gallumphs across desks making paper aeroplanes from blueprints and smashing intricate models of famous buildings. He doesn't know how to work anymore.
It's impressive how nakedly existential Before We Vanish is. Director Kiyoshi Kurosawa revolves his film around foundational questions that most adults have settled on answers for, like, "Who am I? What is love? Why do we fight wars? What is property?" Much of Before We Vanish plays as a comedy and the film mixes quirkiness and tension well. Yet, even as you're laughing at the nihilistic hijinks of the teen aliens, you sit in a sense of creeping dread as they near the completion of their mission. There's something horrible about watching them rob unsuspecting humans of vital concepts after goading them to load up ideas in their heads. When a human falls to their knees after an alien touches their forehead, you know that they have permanently lost a piece of the knowledge that made them who they are.
After she starts off wanting the old version of her unfaithful husband back, Narumi wants to keep this new Shinji. He's kinder, gentler, and more open to experiences the old him had written off. A cranky reporter named Sakurai (Hiroki Hasegawa) finds himself orbiting the alien in a teen male body, tethered by a mix of careerist scoop hunger, morbid fascination, and ornery bitterness. The aliens refer to both Narumi and Sakurai as their guides to humanity's cognitive wilderness but the two humans wrapped up in this chaos find their loyalties challenged. Sakurai spends much of the movie trying to get people -- including himself -- to believe that the alien invasion threat is real. While she's also butting heads with the government agency trying to suppress the truth, Narumi is trying to figure out a routine with this weird, naive Shinji variant in her life.
Kurosawa's film juggles bursts of poignant emotion, sudden violence, and manic comedy with ease. It's fun to watch, even more so because it's designed to make you think. Before We Vanish is reminiscent of Invasion of the Body Snatchers but, here, the organising concern is deep existential questioning, not cold war paranoia. It makes viewers question how the expectations and relationships we have with others define our sense of self and how we re-orient that sense of self when the people around us go through dramatic changes. The extraterrestrials came to Earth to absorb knowledge and discard flesh but what they experienced changed them, too.