Is there any age restriction? What is the meaning of G, PG12, R15+, and R18+?

Except for some movies, preschool children will not be admitted.

These are categories classified by EIRIN (Film Classification and Rating Committee) to restrict viewers’ ages.

G: Appropriate for people of all ages.
PG 12: Parental guidance is required for children under the age of 12.
R 15+: People aged 15 and above will be admitted. ID is required to confirm your age.
R 18+: People aged 18 and above will be admitted. ID is required to confirm your age.