In the game it states that after having the player ID changed, your previous player id name will be available to other users. Is that true? I belive that in the jp version you couldn't change your player id back to an ID which was previously used. Is that a mistranslation or is it actually true? Maybe the old player ID will take some time to be deleted from the database and be reusable? A mod may know the answer... thank you

You can change your Player ID Name by selecting Support Menu on the Start Menu, then selecting "Change Player ID Name". Please keep in mind that this will cost AC to perform (1st time is free).

Note: The Player ID Name cannot be changed again for 30 days once changed.

Note: You cannot change your Player ID Name to an existing or previously used ID.

Note: You may be unable to change your ID to your desired name if it contains forbidden words. In such a case, please choose a different name.

Note: Other players will be able to view your Player ID Name, so please refrain from using personal information such as your real name or phone number.

Note: Please refrain from choosing abusive or distressful names.

Note: Rankings will display information from the time played, so your previous Player ID may be shown even if you change your ID.

PSO2 Manual

Yeah I already checked the manual, don't change the fact in the game itself actually says that previous player IDs are available to other users. I suppose one of them is not telling the truth! Why would they write like that in the game than?

Well if it says that in game must be true then.