First of all, I will write about the variety of Japanese preschool.
Authorized preschool ( It is based on the educational law, and authorized by Tsukuba city. The city pay some money.)
☆day care・・Hoikusho (保育所)----- It is for working mother.
public(公立保育所)--0~until elementary school
private(私立保育所)--0~until elementary school
☆kindergarten ・・Youchien(幼稚園)-----It is more educational.
public (公立幼稚園)---2 years (4,5 year's old )
private(私立幼稚園)---3 years(3,4,5year's old)
Unauthorized preschool ・・(It is limit-free, flexible for time and curriculum. )
☆ private day care
I'll explain each detail next.