You can go to the Ministry of Commerce to check whether this intermediary is qualified. The three-year graduation you mentioned is a short-term university in Japan, and two-year graduation plus short-term events and one-year language school is exactly three years. This is the quickest way. If you want to continue to go to school after short-term college graduation, you can go directly to the third year of undergraduate course, change your major or take the postgraduate entrance examination. Good luck.