The last email from RIPN said that domain names will be transferred to RU-CENTER starting on the 27th of this month. Lao Maozi received the letter last night. Unfortunately, I was in a hurry and didn't see it clearly during the operation, so I didn't remember the contract number until I logged in. I encountered some troubles and was too busy during the day to take care of it, so I haven't written this tutorial.
It's said to be a tutorial, but it's actually very simple. It's just a process. Just don't make the same mistakes as me when you execute it. Remember the contract number.