That is the rule in Tokyo.
Source
“The Age of Consent in Japan is 13 years old. The age of consent is the minimum age at which an individual is considered legally old enough to consent to participation in sexual activity. Individuals aged 12 or younger in Japan are not legally able to consent to sexual activity, and such activity may result in prosecution for statutory rape or the equivalent local law.
Japan statutory rape law is violated when an individual has consensual sexual contact with a person under age 13. At 13, Japan’s base age of consent is the lowest of any developed country. However, many prefectures also have local “corruption of minors” or “obscenity statutes” (淫行条例) which raise the de-facto age of consent to 16–18, unless they are in a “sincere romantic relationship”, usually determined by parental consent. For example, the effective age of consent in Tokyo by local statute is 18. The age of marriage is 16 for girls and 18 for boys with parental permission, and 20 otherwise (as stated in ” ナス邃「窶慊カ窶「ナクナスニ停?邸”, the Child Welfare Act of Japan.
Japan has two territories that have their own local age of consent laws. These territories are listed in the following table:”