hotel register; guest book
A book or record in which guests at a traditional inn or hotel write their name, address, and other details.
旅館に着いたら、まず宿帳に名前を書いてください。
When you arrive at the inn, please write your name in the hotel register first.
Compound of 宿 (yado, 'inn, lodging') and 帳 (chō, 'register, notebook').