When I got iM@S SP I showed it to my sister and she was like "can you show me how to play?" so I taught her how to play in office mode. I opened up pictures of each girl and showed her each one telling her their names and asked which one she wanted to play, she pointed to Yayoi and said something like "tell me where in these moonrunes to go to play her". I showed her then where Yayoi was in the menu and explained how to pick songs and costumes and stuff. I pointed out the katakana for the stats and said what each of them were. Taught her how to play and she played some office mode with Yayoi. She really does like yayoi, even asked me to make a wallpaper for her computer with yayoi on it. :3
As for my parents, they really don't care. I just have to bug them about buying PSN yen cards because I don't have a credit card.

They do their usual "what are they saying, (chinese-sounding gibberish), ahahaha. Do you really understand what they're saying?" In general my parents are cool with my like of japanese stuff.
My mom helps me with cosplays, my dad does voices in dubs on occasion, and my sister watches shows with me (and watches me play some games too). My family's pretty cool I guess.