i'm going to upload a bunch of words in Chinese characters that have to do with ninjas as soon as i can get the pages of my kanji dictionary scanned. There are a bunch of terms regarding ninja and poaching and if some catch the eye, they may help create a good shirt or hoodie.

also, someone suggested that everyone on this forum should have ninja names like Saburo　三郎　 Goemon　五右衛門, etc. But I think that would be far too confusing for gaijin and turn people off.
Hattori Hanzo 服部半蔵 has the idea!