Yeah here you go. 
This is actually interesting, thanks for the link.
Law for Punishing Acts Related to Child Prostitution and Child Pornography, and for Protecting Children.
This is a temporary translated version of the New Law adopted by the Japanese Diet, in April 1999 related to
Child Prostitution, Child Pornography and Sexual Abuse of Children committed by Japanese nationals abroad.
Article 1 - Objective
The objective of this Law is to protect the rights of children by prescribing punishment for acts
related to child prostitution and child pornography, and by establishing measures including the
giving of appropriate protection to children who have suffered physically and/or mentally from the
said acts, in light of the fact that sexual exploitation and sexual abuse of children seriously infringe
I. Ages for legal purposes
Article 2 - Definitions
For the purpose of this Law, a “child” means a person under the age of 18 years.
Age of majority
The Article 3 of the Japanese Civil Code states that the age of majority is twenty (20) years old.
Age of consent for sexual activity
The Article 177 of the Penal Code puts the age of consent for sexual actitvity at thirteen (13) years.
Age of consent for marriage
Articles 731 and 737 of the Civil Code provides that the age of consent for marriage is eighteen (18)
years for men, and sixteen (16) for women.
But when a minor wants to get married, he or she needs the consent of his or her parents.
II. Rape
‘Rape’, Art. 177 Penal Code
" A person who, through violence or intimidation, has sexual intercourse with a female person of
not less than thirteen (13) years of age commits the crime of rape and shall be punished with
imprisonment at forced labour for a limited term of not less than two years. The same shall apply
to a person who has sexual intercourse with a female person under thirteen (13) years of age. "
‘Death or injury resulting from rape’, Art. 181 Penal Code
" A person who commits a crime provided in Articles 176 to 179 and thereby kills or injures
another shall be punished with imprisonment at forced labour for life or for not less than three
years. "
III. Other forms of child sex abuse
‘Indecency through compulsion’, Art. 176 Penal Code
" A person who, through violence or intimidation, commits an indecent act upon a male or female
person of not less than thirteen (13) years of age shall be punished with imprisonment at forced
labour for not less than six months nor more than seven years. The same shall apply to a person
who commits an indecent act upon a male or female person under thirteen (13) years of age. "
Common articles to rape and indecency
‘Constructive compulsory indecency and rape’, Art. 178 Penal Code
" A person who commits an indecent act upon or has sexual intercourse with another by taking
advantage of loss of consciousness or inability to resist, or by causing a loss of consciousness or
inability to resist, shall be punished in the same way as provided for in the preceding two
Articles. "
‘Attempts’, Art. 179 Penal Code
" Attempts of the crimes provided in the preceding three Articles shall be punished. "
‘Complaint’, Art. 180 Penal Code
" (1) The crimes provided in the preceding four Articles shall be prosecuted only on complaint.
(2)The provisions of the preceding paragraph shall not apply when the crimes mentioned in the
preceding four Articles are committed jointly by two or more persons who are on the scene of the
action. "
Article 34 of the Child Welfare Law
" Any person shall not do any of the following acts : …(6) act of inducing a minor to be engaged in
sexual activities … "
Inducing a minor who is less than eighteen (18) to be engaged in sexual activities is subject to
punishment under the Child Welfare Law. According to Japanese Court cases, " inducing a minor to
be engaged in sexual activities means an act of working on a minor to have intercourse or analogous
conducts ( including oral and anal sex) with him or her, or with someone else by exering influence on
the minor virually.
It looks like statiotory rape is 13 (though for some reason I could have sworn it was older)
The other stuff was what I was talking about (18-20)
Ryu