As a fellow 17 year old, I can tell you that there is no reason to not take his flight. Since you're in J, you'll have a nice meal, and (depending on the airline) a flat seat which you should be able to get some sleep in. Bring an ipad and a book as well for entertainment.
Japan is also a great place to visit, it is one of my favorite places ever, and the first international destination I ever went to (when I was 2). However, make sure you research Tokyo before you leave and you'll be fine.
Enjoy your trip!