Because the organizational structure of Japanese universities is different.

Japanese universities are institutions of higher education, as defined by China. Japanese colleges are not independent institutions, but generally branches of universities. Most of them are invisible institutions with no administrative level in universities, and they are also learning institutions in Japanese universities.

2. The education system is different.

The academic system of Japanese universities is generally four years, while the curriculum of Japanese universities is generally divided into two-year doctoral preparatory courses and postdoctoral courses, and the academic system is generally three to five years.