Originally Posted by evergrn

How old are your kids, and do you have elite status with any chains?

There's plenty of Japanese hotels with room types that can accommodate 2+2. But you insist on high-end Western chains.
My kids are 9 and 8. Over the last 4-5 years, we've stayed in many high-end Western places (Hyatt Regency, Hilton Shinjuku, IC Tokyo Bay, Conrad, etc). I generally will book it as 2 adults and 1 child, and then I contact the hotel to ask if it's okay that there's actually 1 more child. It's not been a problem at any of the aforementioned hotels, although I think I've only stayed at IC Tokyo Bay and Conrad since my younger one started elementary school. That's because those are the only chains I have any status of significance at. Depending on the hotel, Japanese hotels have different policies regarding kids being allowed to stay free and share bedding. The age cutoff for that in Tokyo hotels is generally going to be either 6 (or 1st grade) or 12 (or junior high). Rarely you'll find hotels like Conrad Tokyo and Vessel Campana that actually will define free kids as up through 17.

We're pretty slim and our kids are still relatively small, so we can share 120cm wide beds. Twin beds in most upscale Tokyo hotels we stay in are 120cm wide. If you think that may be difficult, well the alternative would be: a).king bed + rollaway for a free; b).ask hotel to stick the twin beds together ("Hollywood twin") as 4 sharing a 240cm bed is far easier than 2 sharing 120cm bed. However, many hotels cannot accommodate (b). I know IC Tokyo Bay can.