Going back Japan after 10 years

I'm gonna give a bit of context. The last time I went to school in Japan was kindergarten, and ever since then I've been living in a foreign country.
It's been 10 years now and due to family reasons, we decided to move back to Japan. By reading this you'd probably assume that my Japanese is pretty terrible, and you're right. I only know conversational level Japanese, I can only read hiragana and katakana, my kanji level is the same as a Third Grader. And don't even get me started on my handwriting, I think a First Grader can write better Japanese than me.
Do you think it's a good idea for me to transfer to a Japanese High School with my level of Japanese? Especially when the entrance exams and all the academics are in Japanese. Are there any programs for English/foreign students?
If this one doesn't work, I am planning to not go to school for an entire school year, instead learn Japanese at home and take the entrance exams a year later when I'm ready. Is this a better option for my situation?

I doubt you would even be accepted even if you tried.

But no you are too far behind for mainstream school.

Haru san
A Lot of years ahead of you.So i strongly suggest you to complete 12 years education in your home country.Then come to japan.

You can attend private international school in Japan, where everything is taught in English (there are other languages). You can also take Japanese language classes in such schools.
Two that I know of in Tokyo are: American School in Japan (ASIJ), and Christian Academy Japan (CAJ).

There are others.

Ref ª:
The last time I checked, you do not have to be a Christian to attend CAJ.

I myself grew up in Japan, but left Japan for two years (due to dadfs work in the US) during my 8th and 9th grades, and came back to Japan in March, so at the end, of my 9th grade. So i missed all the chances to sit for any regularly scheduled entrance exam to high schools. All i had was records of completion from my Japanese junior high (for 7th grade) and from my schools that I attended in the US (for 8th and 9th grades equivalent). My Japanese language was fine, but i was clearly behind in some subjects, such as social studies (including Japanese history) and math.

At that time, i (or my parents) had to search very quickly for a private high school that was open to goverseas returneeh students, through an acquaintance convince them to allow me to at least take the test, and get me to take the test, to get me into a high school.

So if the same things are required, youfd need to make sure that you have attendance/completion record for up to 9th grade, find a school who is willing to give students from overseas a chance to sit for their entrance exam out of their ordinary scheduled timing, and pass the exam. Japanese senior high schools arenft gmandatoryh education, but living in Japan without at least a high school diploma would severely limit onefs future opportunities (for a local that is. I am not sure what nationality you hold).

Hearing that your Japanese language is limited, you gmighth want to try an international school (as suggested above), so that you can learn the subjects in English and at the same time improve your Japanese proficiency; or if you want to take one year to study up, find a private tutor who can help you with the study subjects as well as the language (I do not recommend only self-study). Best wishes.