Check in for two at the hotel.

If only one person's name is filled in when filling in the check-in information, you can try to contact Ctrip customer service, explain the situation to them and ask if you can fill in another person's name.

Before contacting Ctrip customer service, you can check whether the room type you booked allows two people to stay, so as not to be refused because of overcrowding.

If your room type allows two people to stay, but only one person's name is filled in your check-in information, you need to contact Ctrip customer service as soon as possible to explain the situation to them and provide their information so that they can help you solve the problem.

When contacting Ctrip customer service, you can provide information as much as possible, such as order number, check-in date, room type, personal information used when booking, etc. Ctrip customer service will help you solve the problem according to the information you provide.

If you can't contact Ctrip customer service or solve the problem, you can try to contact Prince Shinjuku Hotel in Tokyo directly, explain the situation to their customer service, provide another person's information, and ask them to help you solve the problem.