The policy is to prevent some people from coming back after going there. Therefore, short-term visas (such as travel, business, visiting relatives, etc.) that are not round-trip air tickets are often refused by the customs. Due to the rapid changes in the domestic system, it often happens that you are released today and not released tomorrow. Orz, therefore, is safe to buy a round trip. If you want to fight for character, you can take a one-way trip. If you really don't let you go, you can tell him, especially because you have been there twice before and have a good record twice, so the possibility of release will be improved.

or you can consider buying domestic flights. China International has a half-year /1-year ticket (all the tickets found here are valid for 1-year round trip from Japan to China. It's more convenient to make inquiries at home if you leave from China.)

Airlines don't care about this matter, but the airport customs will not let you go.