Ambivalence prevails in this melancholy study of loyalty and self-sacrifice. Well- served by the superb acting of the lead players and evocative cinematography, Kenji Aoki’s screenplay makes telling use of sparse dialogue. Flashback and hallucinatory sequences heighten the tension, building on slow-paced exposition as we engage with the at-first remote central character. Well-signposted clues lend the credibility to the final scene, and its ability to startle pays tribute to the subtlety of the direction.

Attractive fifty year old Minako (Yuko Tanaka) rides her bicycle through the pearly dawn in her scenic hillside neighbourhood. She carries a satchel of clinking milk bottles on foot up the backstreets of town, which resemble a series of concrete staircases. A familiar face to the gentle old man who drains the bottle whilst she waits and the grey-haired housewife (Misako Watanabe), watching over her wakeful husband (Koichi Ueda), Minako eventually makes her final and most important call. It’s to an address so high up that she needs to encourages herself with a muttered, ‘Here goes’, before darting with her characteristic lightness of step to the house where businessman Keita (Ittoku Kishibe) tends his beautiful wife Yoko (Akika Nishina), who is dying. Having slept on the mat beside her bed, he sets up her medication drip before departing, leaving her in the care of a nurse. Minako spends the rest of her day as a supermarket check-out assistant then returns to her tiny book-lined apartment.

The grey-haired housewife, a writer and Minako’s aunt, reads aloud a story about her niece’s ‘life of perfect regularity’. Minako’s own voice as a fifteen-year old advises her future adult self: ‘Stick to your dream’. Her dream, as we find out, is simply to remain near to Keita, her childhood sweetheart who ended the relationship when their parents had an affair.

Successive contrasting episodes reveal Minako and her world. They include stumbling on a male supervisor fumbling with a female employee in the stockroom, politely refusing to join in gossip sessions with her frivolous colleague and an evening’s drinking and photo-album reminiscing with the gentle-natured aunt. Sharing Minako’s stoical outlook, she’s determined to care at home for a husband slowly succumbing to dementia.

‘There’s nothing wrong with living alone. Just tire yourself out and you’re fine’, is Minako’s advice to the flirtatious young colleague when the supervisor loses interest and goes on to the next conquest. The traditional attitudes of the older women, and the Haiku-composing Keita contrast with Minako’s supermarket colleagues. When Keita persuades colleagues at the bureaucratic children’s department to rescue two boys from their addict mother it points up a wider social malaise.

As Keita’s wife’s condition worsens and she learns of her husband’s old attachment she realises she must act to bring the pair together again before it’s too late and contacts Minako by leaving a note with the empty milk-bottle. The pace quickens as the confused old man wanders the streets and Keita leads his colleagues in a raid on the abusive mother’s home. Emotions supressed for 35 years overwhelm him and he and Minako are eventually forced to come to terms with their past.

A Satie-like piano accompaniment, subdued before to foreground Minako’s breathing as she skips up the steps, is augmented by urgent strings during the dramatic climax. A final act of retribution is lightened by a subtly ambiguous twist.

‘The Milk Woman’ is from ‘A Life More Ordinary: A Portrait of Contemporary Japanese People on Film', a touring film season produced and organised by the Japan Foundation It is at the ICA in London 9th-14th February.