Pre-post edit: Oops I started typing and I didn't stop. :V
I jelly.
I suppose it helps that my parents are both long-time gamers, so naturally my siblings and I got into it as well.
They'd probably have never found Touhou though, so I'm taking all the credit for being the one interested in Japanese things. :V And so, my addiction has spread to everyone.
It might not work for everyone, and some families are, unfortunately, very strongly anti-japanese (can apply to anti-anything really) and so would ignore it completely. Something I would never agree with, but it happens. But if you think you've got even half a chance, I'd recommend anyone to try and get their family and/or friends into it, as long as you don't force it on them as that tends to backfire and drive them away.
Something as simple as "Hey, check out this cool picture I found!" or "Hey, try listening to this! Found some pretty nice music." can get some amount of interest, without being too much at once.
You can try to target their interests too I suppose; if I had a friend who loved vampires I might show them the Scarlet sisters. Really this is so easy. We've got mikos, witches, puppeteers, maids, vampires, bookworms, fairies, bugs, birds, rabbits, immortals, phoenix, cats, foxes, zombies, (half-)ghosts, mouses, captains, various gods, things who's true form is unknown, drunk onis, jealous people, people in a bucket, musicians, mind readers, hell ravens, mokou, etc etc etc (ignoring all technically correct names because they don't usually care)
Things like [F: "Hey *name*, what're you playing?" You: "Oh, it's a pretty fun shooting game I found. Wanna watch?"] kind of things can work too, as long as you don't scare them away with 9001FPS Lunatic runs or something. :getdown: Let them watch easy mode or something, because if they say it looks too easy you can just go up from there.
Well I dunno why I started typing in the first place but I better stop before this becomes a huge wall of text. :V [/randomaddictingadvice?]