Before We Vanish starts with a delicious flurry of black comedy flourishes. A schoolgirl walks toward a house with a goldfish in a plastic bag, followed by an ominous soundtrack rumble and a touch of lens flare, then a woman comes out of the front door, whom we then see being dramatically yanked back inside… The sequence culminates in a wonderfully casual bit of traffic chaos, to an incongruously flip passage of oompah-oompah music from composer Yusuke Hayashi. We’re in for a story of alien apocalypse, but in a mode that’s a little more insouciant than we might usually expect from Kiyoshi Kurosawa.

This director has specialized in the past in subtly weird science fiction or horror, often built around a single off-kilter premise—a sentient tree (Charisma), a jellyfish explosion (Bright Future), people turning to black stains on walls (Pulse). Recently, however, Kurosawa has been exploring different territory: supernatural romance (Journey to the Shore, 2015); a thriller, Creepy (2016), that starts out Hitchcockian before shifting into the type of crazed intensity you’d normally associate with Shinya Tsukamoto or full-freak Takashi Miike. He’s even tried his hand, gamely but disappointingly, at a European ghost story in the awkward French-language Daguerrotype (2016), with Tahar Rahim and Olivier Gourmet.

Based on a play by Tomohiro Maekawa, Before We Vanish—its Japanese title means “Strolling Invaders”—may not be prime Kurosawa, and it’s oddly uneven in tone, but it has an ease about it that’s intensely engaging. It’s about two characters who come into contact with people who started out human, and still look human, but fundamentally aren’t. In fact, they’re a trio of extraterrestrials who have come to Earth to prepare for an invasion, during which all humans will be wiped out, except for a few who will get to live on as “samples.” I’m not spoiling anything by telling you this, as one visitor explains it all early on, in a remarkably matter-of-fact fashion; there’s nothing like being upfront about your premise.

Another key bit of exposition is also dealt with bluntly from the outset. The alien scouts, which take over human hosts in the time-honored manner of Invasion of the Body Snatchers, learn what they need to about Earth culture by harvesting “conceptions,” as the subtitles put it. With a finger to their informant’s forehead, they glean the meaning of key earthling abstractions such as “work,” “family,” and “freedom”—at which point the human loses all knowledge of the concept in question. This is the film’s neatest idea, with effects you can imagine. A woman who’s lost the notion of freedom bows and scrapes in gestures of domestic servility; another, who’s just yielded the meaning of family, acts like a total brat towards her sister; an abusive boss, milked for the meaning of work, starts capering around his office like a destructive child, smashing all his design company’s treasured maquettes.

And yet, with loss comes liberation: giving up the notion of “possession” (as the subtitles have it, although “property” might have made more sense), a man no longer has to hang around his house and instead becomes a free-ranging prophet of the new age. Preaching outside a mall, he tells a bemused audience that he’s let go of his old self and that people should do the same. We’re on verge of war, he says, yet we hang onto things we don’t need—and in a near-subliminal touch, we can just see a Toys “R” Us banner in the background.

There’s a provocative notion at work here: that if we were to slough off some of the inherited social concepts that determine our humanity, we might get to be fully human in ways we can’t yet conceive (imagine there’s no heaven, and so forth). Before We Vanish works through these ideas, often a little heavily or wordily: a detective, stripped of the meaning of “self,” falls into an abyss of uncertainty. “Who are you?” he asks the first person he sees. “Yourself or another?”

But the film works best when it’s simply dramatizing the confusion of the humans who get embroiled in the invasion plot. One is a young woman, designer Narumi (Masami Nagasawa), whose husband Shinji (Ryuhei Matsuda) is hospitalized with a strange form of blankness, stumbling around uncomprehendingly like Dale Cooper’s alter ego Dougie in Twin Peaks. Eventually, he tells Narumi that he’s an alien in Shinji’s body, and asks her to be his guide; fortunately for the purposes of the narrative, guide humans are exempt from the mind-stealing process. This means that a bemused Narumi can accompany Shinji on his wanderings, and also that Sakurai (Hiroki Hasegawa), a jaded TV reporter, can plays escort to two aliens: a strange, smiling young man called Amano (Mahiro Takasugi, whose strikingly limned face actually looks as if he’s been drawn for an anime) and Akira (Yuri Tsunematsu), the girl from the opening sequence.

The three invaders have entirely different personalities, or perhaps embody complementary aspects of human nature: Amano is utterly pragmatic, focused on the tasks to be carried out; Shinji is the bemused intellectual, discovering the strangeness and rapture of comprehending the new world he’s in; and Akira is basically the Id, the natural born killer among them. The bad-to-the-bone schoolgirl is a much-fetishized trope in Japanese pop culture, but Akira might be the one to end them all: a fast-kicking, hard-fighting embodiment of instant death who’s never more than a moment away from grabbing a convenient machine gun, or—in one of the film’s snappiest effects—slamming her pistol-toting fist through a car windshield.

Kurosawa throws in some stylistic dazzle from time to time: a great sequence with planes zooming out of nowhere, as Sakurai faces imminent apocalypse in bring-it-on mode, and a brief (two-and-a-half-minute) but bravura single-shot moment in a hospital, as people freak out in every direction, an army detachment marches through, and a man in a protective suit goes into abrupt meltdown. Kurosawa only intermittently broadens his focus beyond the central characters but when he does, he acutely captures a sense of mounting social derangement, with echoes of George Romero’s The Crazies.

There are two redemption stories in Before We Vanish—three if you count that of humanity itself, which might be in with a chance of regaining some dignity before the crunch comes. One belongs to Sakurai, an ambivalent character who seems happy to join the aliens as enabling guide, but who is also determined to transcend hackdom and go for broke to get the biggest story of all time. “Can I write about you?” he asks Amano. “Just as you’re about to be invaded?” replies the boy. “You humans are awesome!” Incidentally, much of the script seems to be about language in a way that the subtitles may not always fully capture. While Amano speaks in a fashion that’s translated as international Anglo-American youthspeak—“Dude,” “Whatever”—a lot seems to revolve around the difference between the name “Shinji” and the informal version or pet name that Narumi uses, translated here as “Shinzy.”

As for Shinji, his is the other redemption story: although whether it applies to the human Shinji or the presence that occupies him is a moot point. The film has much more to say about the strangeness and radical uncertainty of alien contact than the much-vaunted The Shape of Water, whose heroine doesn’t seem to find it too odd that her heart’s a-flutter for a denizen of the deep: it seems that, once she’s tempted him with a hard-boiled egg, he’s just a regular dream date, only wetter. By comparison, Kurosawa not only captures humans’ puzzlement at alien otherness, but the aliens’ own anxiety too. “I’m confused,” says the being inside Shinji. “Has Shinji become part of me, or have I become part of him?” Pause. “Either way, it’s OK with me.” It’s eventually OK for Narumi too, although she’s not entirely sure what kind of entity she’s been driving around with. “Why not act more like an alien?” she asks. “Shoot death rays from your eyes?” The thing that’s become her husband shrugs: “That’s not Shinji.”

You may not be surprised to know that the story’s payoff concerns love, the effect of which can be seen in a somewhat sappy coda. The one moment that might make you squirm comes earlier, a scene where Shinji stops into a church and asks the priest to explain the meaning of love—at which point, the smiling young cleric regales him with a key passage of Corinthians (“Love suffers long and is kind…”). But when Shinji sits down and heartily enjoys Narumi’s home cooking, which he’s never much liked before, we realize that he’s found a more concise and direct definition of love. Given the stakes of the story—nothing less than humanity’s total annihilation—Before We Vanish is a surprisingly domestic, sweet-natured affair. It must rank as one of the least paranoid aliens-among-us movies ever made; in Kurosawa’s own filmography, it goes to show that for sheer strangeness, even extra-terrestrials can’t compete with trees or jellyfish.

Jonathan Romney is a contributing editor to Film Comment and writes its Film of the Week column. He is a member of the London Film Critics Circle.