I nearly forgot, I know yet another student who studied abroad in Japan as a high school junior. He didn’t apply to any Ivy schools, but his essay was a great read and he now attends the most selective public college in New York. He also loved his experience and speaks Japanese fluently.
If you are going to be a regular student in a high school, presumably studying regular subjects, AOs aren’t going to hold it against you that didn’t take MORE AP classes, instead of going to Japan.
Your application is assessed in terms of what classes are available to you and how you compare to other students at your school. Admittedly it won’t be as straightforward to compare your three years at Jones High and one year at Tanaka High to Sally Smith’s app with four years at Jones High. But so what? You don’t need to be like Sally Smith.
Have your experience, and apply to MIT or wherever. If you are a strong applicant, a year of study abroad isn’t going to ruin your chances.