In Japanese schooling system teachers are not qualified in subjects which they have to teach, because a teacher usually teaches some irrelevant subjects such as English teacher teaching science or maths, but in Europe every teacher must have a university degree in that particular subject which he wants to teach.
They do need proper qualifications to teach core subjects such as science, math and English. But when it comes to secondary subjects such as art and technology or geography, teachers with proper qualifications are in short supply. Oftentimes, math teachers also do IT classes without a degree in IT.

The biggest problem with the Japanese school system is strict school rules. Dating is strictly prohibited in most schools, which may contribute to the country's low birth rate as students grow up believing that dating is a sin, while teachers behave like drill sergeants toward students to enforce school rules. Because of the oppressive nature of teacher-student relationships, students cannot enjoy school life and they don't dream about becoming a teacher.