I am a priceline member. I needed to book a hotel in Japan for family trip so I thought I would use them.

It is a regular hotel reservation, not the "name your own price" kind.

I do all the regular selection. Entering adults, number of children, their ages, location, date. Pick a hotel and made my reservation. And then, the confirmation came and it looks a little fishy. My 2 adults, 2 children reservation turned into a 3 adults reservation. I decided to contact priceline. Who told me my reservation is made through booking.com (?). So, I contacted the hotel via booking.com and the reply I got is: I am not allowed to check-in with that reservation because my party exceeded the guest allowance! (Priceline shown max guest is 5, and it charged me extra for 2 children)

I am glad I read the confirmation and checked with the hotel. I don't know what would happen to me when I found out during check-in. Just thought I would share my experience so you don't run into the same issue.

Priceline, Agoda, Kayak, Cheapflights etc are all owned by booking.com. Many OTAs will send your booking to another OTA before it hits the hotel.

Simple solution: don't use an OTA.

Am busy today, but in post #19 in this thread
Marriott/Hilton or Business Hotel (like Dormy inn)?

are my suggestions for rooms that will accommodate 4 in central Tokyo.

Back in the day when priceline wasn’t part of Booking.com, its main use in Tokyo was as a way to get the IC Tokyo Bay (near Hamamatsucho) at a discount. They have (or had) rooms with two double beds where 4 people can stay.

Thanks for the advice. I tried Marriott and most of them also don't allow 4 guests per room even if I enter the ages of children. For the ones that allow, the prices are prohibitively expensive. I am leaning toward just booking 2 rooms. It doesn't cost much more because of price gauging when adding 3rd and 4th guests to 1 room.

Something rather strange from the hotel's reply is: "For safety reasons, children of elementary school age and above are required to have their own bed.". I don't know what kind of "safety" the hotel is talking about that children need to have their own bed. How would that be safer?

Child becomes �adult� at 12 in most Japanese hotels (those that don�t exclude them entirely).
Worth noting that the age of consent is still 13 in Japan.

If the second child is still under 12, there are quite a few hotels with a �child stays free if using existing bedding� exemption. In the past, I�ve made award redemption bookings that don�t accept kids in the search criteria for two adults and then contacted the hotel after the fact to advise them that a child using our bedding was staying with us. In your case, you�d need to find a hotel that allowed a child to share bedding in a room booked for three adults.
We found the process quite tricky at Western Hotels and only had the one child (she�s 13 now). It is rather more straightforward at Japanese style lodgings.

Or see if any of the options in that other thread suit your family.

Priceline is a really bad idea. I tried booking a hotel has a priceline quote that is cheaper than others. This time I played safe and book as 2 rooms, 4 adults total. Priceline confirmed my booking. But 10 minutes later, I got 2 emails from agoda saying my reservation is cancelled due to payment issue (my card is perfectly fine, as I used it without issue afterward). But Priceline still showing my reservation is fine and dandy. It would once again be a disaster had I ignore the agoda email and show up for my hotel.

In summary. Don't book your oversea hotel using priceline, especially if you are traveling with kids. You could be in for a rude surprise.

i've mostly used agoda (& direct) for japan hotels

agoda plays games with pricing & coupons (going through different portals, you get different coupons and prices), and sometimes the description is lacking/strange....

but never had an issue, always got the room I expected to get. agoda is almost always cheaper than other travel agencies (even their family of companies - eg booking.com)

I agree with the above, I have mainly used Agoda since their prices are usually below other TAs and haven't had a room rejected or hidden fees pop up. The other site I have used several times is Trip.com who, besides Agoda, has some of the lowest prices.