Kotoko

"Hang tough, Japan!" exhorts the man on the television set. It is a subtle acknowledgement that production on Shinya Tsukamoto's Kotoko took place in the shadow of the 2011 Tohoku earthquake – for here, as in Himizu (2011), an isolated individual's psychodrama unfolds against the backdrop of an entire nation in catastrophic ruins, even if we never, unlike in Shion Sono's film, see the tsunami-devastated landscapes of Fukushima. Rather, Tsukamoto's film begins with images of a little girl dancing with abandon before the open sea, until a tidal wave of frantic screams floods the soundtrack.

In her adulthood, Kotoko (co-writer Cocco) is no less overwhelmed by her environment. "I see double," her voice-over reveals, and what she sees, we see too: a threatening world where the ordinary people that she encounters in her daily life are accompanied by menacing, aggressive doppelgängers, who launch into violent attacks with little warning. Of course, this is all in Kotoko's mind - she is a textbook case of paranoid schizophrenia, even if the term is never used in the film – but Tsukamoto rarely if ever departs from her headspace, so that the film's narrative takes on an unreliably duplicitous status that becomes more and more alarming with every scene.

Like Lodge Kerrigan's similarly subjective Clean, Shaven (1993), Kotoko shows us mental illness from the inside, dividing viewers between sympathy with the protagonist, and a nagging nervousness at the ever-present possibility that what we see her and others doing just might be real rather than merely delusional.

On top of all this, unhinged, self-harming Kotoko is single mother to Daijiro, who is the focus of all her love, but also of all her anxieties. Convinced that her phantom persecutors wish to do harm to her son, Kotoko confines the infant to her apartment in a bid to protect him, even as her own behaviour seems ever more erratic and dangerous. After an incident that makes the authorities (and us along with them) suspect Kotoko of abusing her own child, Daijiro is taken into the care of Kotoko's sister. Now left on her own and suffering considerable anguish, Kotoko finds herself being courted by softly spoken novelist Tanaka (Tsukamoto), who appears from nowhere to tend her self-inflicted wounds, to take the bruising blows of her every violent impulse, and to give her the unconditional love she so craves – although whether he is a flesh-and-blood person, or a self-preserving projection, is never entirely clear. With Daijiro restored once more to her care, Kotoko regresses further, culminating in a final act that is as harrowing as it is deeply moving.

The depiction of harm to young, obviously distressed children remains one of cinema's last taboos, ensuring that Kotoko is never easy viewing. Reminiscent of Asia Argento's similarly confronting The Heart Is Deceitful Above All Things (2004) in the way that it shows a mother-son bond enduring extreme dysfunction, but deriving its point of view entirely from parent rather than child. Kotoko deploys frenetic handheld camerawork, occasionally piercing sounds and moments of lo-fi animation (hand-crafted by Cocco) to lock us into its heroine's fragmented, panicky perspective. Knowing that Cocco, an Okinawan folk rock singer (who also sings here), was herself prone to self-harm in her youth, or that Tsukamoto has himself made a film with a similar title (Bullet Ballet) to the debut novel ascribed to his character Tanaka, anchors the narrative to a reality that is, of necessity, only partial – but for all her unhinged behaviour and chimerical excursions, Kotoko's intense emotions always ring true.

Those familiar only with his Tetsuo trilogy will associate Tsukamoto with the punkish outer limits of science fiction, but Kotoko, with its human concerns, is more akin to the filmmaker's Tokyo Fist (1995), Bullet Ballet (1998), A Snake of June (2002) and Vital (2004), all of which locate jarring fantasy sequences in a damaged brain rather than in the real world. This is a difficult film, full of abhorrent behaviours and unbearable tensions – but at the same time it shows a profound respect towards its troubled subject, and therefore towards its viewers as well. There may have been wave after wave of cataclysmic destruction, but there is always the possibility of recovery, or at least hope for the next generation.