The capsule hotels in Tokyo are yet another example of the Japanese attitude toward efficient use of space.
Capsule hotels offer guests a very small space to sleep at night, along with the use of common bathrooms. The big hotels integrate onsens as well.
They are budget-friendly by Tokyo standards, and if you're wondering why a resident might subject himself to such a tight space, consider that it's the perfect solution for workers who might get drunk at a happy hour and not be in a position to return home for the night.
After my less-than-ideal experience at a Japanese onsen in Kyoto, I decided not to go to a big capsule hotel.
The reviews I read online made them seem less than desirable, though I suspect part of that had to do with the culture shock foreigners faced when experiencing their first onsen.
Instead, I chose the Ace Inn Shinjuku, which had a whole floor devoted to glorified bunk beds encased in wood paneling, with privacy curtains and external desks.
It was actually rather fun to spend the night there, mostly because I had wi-fi access and could camp out in my little space and not be bothered by whoever else was in the room.
It reminded me of the sleepovers I'd had as a kid, where we'd build forts out of couch cushions, blankets, and whatever else we could get our hands on.
The cost was $50 per night. For $10 less per night, I'd stayed at a Lonely Planet recommended boutique hotel in the capital of Laos.
But this is Tokyo, where cheap hostel dorm beds start at $40 per night, so I chalked the difference up to a little privacy for my final night in Japan.