Those are sometimes a reward for various forum events.

Activation Codes can be obtained from Special Events (Like last Christmas event) and Surveys made by the Naruto Online Moderators which are usually found here in Official Forums - News Section .. As of now, there's is one way to get 1 Activation Code, use Google Chrome to login your account and then click the "Activate Flash" which is located above your screen (beside the servertime - reference image below) ..

Always visit and check our Official Forums, specially the News Sections since our 2nd Anniversary is coming, maybe the moderators will put up a Special Event where you can obtain 1 or more Activation Code ..

Note : The "Activate Flash" way is only good for One(1) account per Code .. So no matter what, or you go to new opened server, it will not work again if you already redeemed one ..

..

Yupz, events are one of the easier ways to obtain Activation Codes to redeem. I recommend keeping an eye out for forum events and announcements. We will definitely update you guys if there is an event that gives Activation Codes.

~Jib