While tattoos are relatively meaningless in the West, they have special meanings in Japan and Okinawa. This meaning can end up closing doors for you. You will have a hard time getting some of the old guard taking you in if they see them.
Tattoos in Japan are frowned upon. They are the sign of the Yakuza and were usually obtained in jail. So if you are planning on training there it may be better not to get a tattoo since the Japanese can be very traditional and their culture is very rigid and teachers can be embarrassed and offended about a number of things we would not even think about here. I'd hate to be refused at a dojo for a tattoo. It simply isn't worth it to me. A tattoo on your back will still be visible in the locker room and there are also Kata in Karate that are run without a shirt/gi top.
BTW did you know that when the Japanese invaded Okinawa the Okinawans tattooes their women to keep them from getting raped? The Japanese would not touch them because they were marked.
Everyone has their own opinion regarding tattoos. Some people like them some don't. Some business organizations accept them some don't. Depending on you career path some will not hire you because of a tattoo or they may require you to have them covered at work. While this may seem to be unfair they are perfectly within their rights as an employer to maintain their company image to their prospective clients.
I am unaware of any martial schools or organizations that has any rules regarding tattoos.
if you want to mark up your body that is your decision, i could care less
What is the view on tattoo and martial arts? especially karate
