Is the second return of Japan necessarily the original company?

No, according to official website, Japan, the planner of studying in Japan, doesn't need to go back to the original company for the second time. Japan's dual-return policy is a reform of the original trainee system. According to the new policy of returning to China for two trainees in Japan, those who return to China within 1 year can return to China twice and continue to work for two years.