Okay the how:

You create a new account (which you have)

-1(from the forum on the new account ) Go to settings , Go to "My Customer Service"

-2(In-Game on the new account) Click your name next to the little person icon on the top right ,Go to "My Customer Service"

Submit a ticket about the lost account to customer support from the new account.

They'll respond with the proper appeal format detailing what information they need to prove ownership,

Once the proper filled in "appeal ticket" has been submitted. They'll look into the appeal claim and contact you in responses to the ticket for any additional information.

Simply follow CS-teams instructions and requests on the ticket responses and you should be able to regain access assuming you did not violate TOS etc.

I am NOT staff nor speak for any facet of Naruto online/Oasis, just another player that has had to go through this before.