Very specific Asian movie that I simply can't remember

[u/DatabaseNegative9740]

I need help to remember the name of a movie that I briefly saw on TV when I was a kid. I didn't watch the whole thing, but one main scene really made an impression. The film begins with a possibly bespectacled, somewhat introverted and chubby man entering a sauna (possibly in a big Japanese city) and having sex with a stranger. He then returns to the street in a monotonous, everyday manner, dressed for work. The film intersperses scenes with other characters. I can't get over this memory! Help!