Despite the problematic aspects of this story, I have to say I'm pleasantly shocked that an Archie comic from the 1970s would bring up the Japanese internment camps. I don't think most Americans during that time were even aware of that shameful moment in our history, so if this comic, stupid as it is, was able to educate some kids about this, then it was worth the paper it was printed on.
Reinforcing the stereotype that the Japanese (and supposedly all Asians) are proficient in the martial arts. However, I didn't know there was one that Japanese know all about gardening. I thought that stereotype was owned by the Mexicans. Who knew?
Re: Japanese gardener, I assume it was a reference to bonsai.
Yeah, Japanese gardeners were a stereotype of long ago, along with Swedish janitors and African American maids. In a rather bad "Lucy Show" episode, Lucy posed as a Japanese gardener, complete with stereotypical accent ("Horrywood"), in a scheme to keep her favorite soap opera from being canceled.