This is the first time I encounter this situation, other items can still be traded. I'm trying to exit the game, reset the internet but nothing changes.

Hi. Thank you for contacting us about your issue.

Do not worry, you did not do anything wrong. You see, the Akatsuki robe is one of those PvE items that sometimes becomes tradeable for a month. The tradeable PvE items are listed at the beginning of each month via an announcement on the official Discord (example provided in the screenshot below, it is the announcement for this month of September).

Unfortunately, for this month of September, the Akatsuki robe is not listed as a tradeable PvE item, thus it won't be tradeable to other players. It is possible that maybe next month it will be tradeable, but we cannot say for sure unfortunately.

We hope this information will be useful to you. As this answers your query, I will now lock this thread. Please feel free to come back and ask if you have any questions in the future and good luck in your adventures!

- Kubrick