Aren't there a crazy number of convenience stores everywhere in Japan, and where not, there are vending machines? Also, I find something incredibly cozy about my city going to sleep at night. Almost nothing is open, not even most convenience stores, and I just find that so cozy.
as for the number there are indeed a staggering amount, at one point i was stood somewhere in Asakusa at around 3am, not a soul on the streets other than me but a cursory glance around and i could see 4 different kombinis that were open
vending machines too are everywhere but they generally just sell drinks, ive never actually seen the supposed underwear vendors of myth, around sinsekai in osaka i saw many vendors selling beers/sake/whiskey however unlike the cigarette vendors they need no age verification, they just politely ask that those under 21 dont use them. the strangest things ive seen were a vending machine for Tenga masturbators in sapporo, a dashi (fish stock in plastic bottles with a large fish crammed in there) vendor in denden town and in sinsekai i saw a gatcha machine covered in pictures of arnie in his prime which had vibrators in
Arnie gatcha: https://photos.app.goo.gl/Tat22AUq7UaEK8ueA Dashi Vending machine: https://photos.app.goo.gl/cGJ2Uko1fGMz9zUs8 Beer & sake vendors: https://photos.app.goo.gl/TMHPn2Z7326L8Rxo9