Easy as pie!
The process of checking-in is similar to that of hotels in other countries. You should go to the front desk and tell them your name and other information to do with your reservation. From that point onwards, the employees will guide you on the use of the room ticket, meals, how to get around, when you should check-out, etc. The process is very straightforward so do not worry! Also, at large and well-known hotels, some or all of the employees would be able to speak English. Therefore, do not worry about the language barrier!
RieS
Japan