Variety's review of "Diary of a Mad Old Man" finds Wayne Wang's first feature since 2019 a disappointingly tepid update of Jun'ichirō Tanizaki's 1961 novel, in which a stroke-afflicted retiree becomes fixated on his daughter-in-law. Despite the provocative premise, the reviewer argues the film ends up dull, chiefly because first-time screenwriter Kelvin Wyles softens the source material's selfish, lucid narrator into a more sympathetic figure, undercutting the novel's darker force.

The film stars Lily Franky as retiree Utsugi, who pursues his daughter-in-law Satsuko (Fan Bingbing) through voyeurism and gifts of jewellery rather than any expectation of sex, while modern touches such as vaping update the setting to present-day Tokyo's Ginza district. Franky, at 62 notably younger than his character, gives a convincing portrayal of left-side paralysis, and Satsuko is reworked into a more rounded character with a backstory, though the reviewer says this fails to make her more compelling. The film also implies Utsugi suffers from dementia rather than simply acting on lifelong desires, aligning it with recent films exploring elder sexuality and dementia, such as "Teki Cometh" and "Familiar Touch".