What grade or year would I be in Japan?

At the moment I am 13 years old and a freshman at my high school. At my school I already get questions like "did u skip a grade?" because I am a year younger then almost everyone. When I move to japan will they base my age, and send me back to middle school?

Junior High School in Japan is grades 7-9 and generally ages 13-15.

If you are born between April 2, 2003 - April 1, 2004, you are a Year 1 at Junior High School(Chugako) in JP.
If you are born between April 2, 2002 - April 1, 2003, you are a Year 2 at Junior High School(Chugako) in JP.

@ VioletViolations
https://en.wikipedia.org/wiki/Education_in_Japan
Jump to "School grades" from "Contents".

@ tokyo friend 48
嶄僥丕/ちゅうがっこう is NOT "chugako"
"ch┗gakk┃" (by Hepburn romanization with tone mark /if browser encoding failed click bellow)
https://s32.postimg.org/7gotty9gl/roman.png
"chugakko" (by Hepburn romanization tone mark less)
("u" and "o" are long tone/long vowels: �L銚咄)

@ 8C, it's NOT "bellow". It's "below".

So what year are you in now? Probably in 9th? Then indeed you must have skipped one year. If you are 13, you are likely to be placed in 7th grade in Japan, so that might mean junior high/middle school. But also please note that the school year starts at different timings between US and Japn, so they (the school) would probably take that into consideration when deciding where to place you.

I think there is no skipping and no delaying in elementary and junior high schools in Japan.