well to be silly I'd get a small cubchoo and croconaw tattoo or maybe the kanto gym badges on my chest if I want to be more serious then I'd get tattoos that match the ones hito-shura (the demi feind) from SMT: nocturne
http://megamitensei.wikia.com/wiki/Hito-Shura
http://megamitensei.wikia.com/wiki/Hito-Shura