1st step: private or public (tax run)

This website focuses on public schools.

private school=shiritsu koukou/watakushi-ritsu koukou

public school=kouritsu koukou

2nd step: age

On the 2nd day of April, how old is your child?

If 6, s/he'll be in the local school called "Shou-gakkou(=grade 1 to 6)" in the April.

If 12, s/he'll be in the local school called "Chu-gakkou(=Chu-gaku=grade 7 to 9)" in the April.

If 15, mandatory education has finished.

All children can't jump classes/grades except grade 12.

3rd step: where do you live?

Grade 1 to 9 are administrated by cities/towns/villages(the smallest administrative unit in Japan).

Grade 10 to 12 are administrated by each middle-level administrative unit.

They're:

43 prefectures as "ken"

Toukyou as "to"

Kyoto & Osaka as "fu"

Hokkaidou as "dou".