[Zakiazigazi]

Generally they are kept very clean and the photo is not at all unrealistic. The cultural norm is to never litter, instead if necessary trash is taken home with you to dispose of for example.

That said, what might contribute to the cleanliness in the photo though is that it was possibly taken after the last train (all trains stop after around midnight), so it's not unlikely the stairs are exceptionally clean because they had just been cleaned before.

On a slightly unrelated note regarding having to be vacuumed constantly, the stairs being clean and the extremely low rate of unemployment in japan might not be unrelated, and on topic it might also not be unrelated to the prevalence of sleeping in situations that would be utterly unacceptable in other countries, such as meetings :)

[coredog64]

You pretty much have to take your litter home. There's no such thing as a public trash can.

[wahnfrieden]

Convenience stores (which are everywhere) frequently have bins outside.

[Pamar]

Most bins are exclusively for cans (sold by vending machine you can find literally everywhere).