I stayed for one night with my son in a super loft-bed room.
The hotel is very close to Ueno so it was no any problem to find. The stuff welcomed and checked in very fast. They don't have room keys. Instead of keys they give a 6-digit room pin code written in a piece of paper.
The room was clean and very very small but that was not a problem.
What was dissappointing that the stuff on reception works till 10pm so when I found at 10:15pm that there was only one sheet for a loft bed (it was just a pile of blanket, one sheet and a pillow on a bed) it was impossible to find another one. Did they think that a child should sleep under bare blanket??
Second dissappointing point was breakfast (free, included into a room cost). Cabbage salad, 3 kinds of bread, a soup and milk. That's all. They called it 'healthy breakfast'. If I knew that I'd prefer to stay in another hotel with greater variety of breakfast dishes.
