Japanese juvenile law

 was established on July 15, 1948 as Law 168. 
Etymology.
According to Wiktionary, 少年 (pronounced as shàonián) originates from Mandarin. 少年 evolved into other pronunciations as Shonen (japanese) and a similar pronounced word with a similar meaning in Korean as 소년 (sonyeon). The word 法(fa) originates as a han character. It contains the same meaning(law) as the japanese character (法) except being pronounced as Ho.
Legal definitions.
According to Japanese law, the term "shonen" refers to "a person from the time they enter elementary school until the time they are 15 years of age", and "Any person who has not reached the age of 15 years" (, Article 2.1). In the realm of education and culture, this is the period of compulsory education. While the term "shonen" can refer to both young males and young females, the generally accepted term for young females is "shōjo".
The following meanings can also be inferred from "shōnen" (a person under 15 years of age) with regard to juvenile law in Japan:
Usage as a demographic term.
The term is also used as a demographic term describing media whose target audience consists primarily of adolescent or pre-adolescent boys. Shōnen manga is a popular demographic of Japanese manga, and often features a teenage cast as well as a combat based plot while exploring themes of protecting loved ones, mutual understanding and development of friendship/camaraderie.