I'd say go for it, but tread cafefully. I've heard too many stories of friends trying to push things a bit further, and in the end, it doesn't work out, but the friendship is destroyed too. You may have to be a wee bit patient and wait for an opportunity to come along. I'm a wee bit jealous actually. Not only a nice Japanese girl whom you know in person, but Japanese class aswell. Well, thats just amazing.