School enrollment in Japan for my kids (6 & 3)

Hi everyone,

I was recently granted a Highly Skilled Professional (HSP) visa and I’ll be moving to Tokyo this September. My wife and kids are applying for dependent visas and the plan is for them to join me in December.

I have two children:

• My daughter just turned 6 in July and is starting 1st grade of elementary school here in Mexico this September.
• My son will turn 3 in October and we would like to enroll him in kindergarten in Japan.

My question is: when my family arrives in December, will it be possible for my daughter to join 1st grade in a Japanese public elementary school starting in January (and then continue into the new school year in April)? Or would she need to wait until April to begin? Also, my wife is teaching her a little bit of japanese, but I'm not sure how hard would it be for her to adapt when joining the new school

Also, how does the process usually work for enrolling a 3-year-old into kindergarten (yōchien or hoikuen) when arriving mid-year as a foreign family?

Any advice or experience would be greatly appreciated!

Thanks in advance