What are the biggest misconceptions about Japan?
I've answered this question in detail, but I think it's worth reiterating some things.
Claim: Eating Lunch on the School Roof is normal
Verdict: Mostly False
Explanation: Eating lunch on the school roof is actually banned in most schools. Generally, students will either eat in the cafeteria or in their classrooms. This is usually a gimmick put into anime to make it more interesting, and it usually doesn't mirror the true environment of most Japanese schools.