In the case of hotels/ryokan that have a special rate or charge a fee for children or infants, the following age groupings are standard:
Infant (0-2 years of age)
Child (3-12 years of age)
Adult (13 years of age and older)
Some hotels/ryokan offer bedding and meals for children, but these services are typically not available for infants. In general, infants are expected to sleep together with their parent(s) or guardian