I have been drawing for quite a while now and it took me years to knack so you`re very fortunate. Some of the pieces you posted are stronger than others, speaking strictly for myself of course as I always do, and to get better you need to draw every day.
Last time I was back in Canada I opened an account on G-mail to stay in touch with Japan, and I have been spending a lot of time over at Google, joined several art communities and if you think you have a knack, you should mosey on over there, join an art community or two and see what people with a real knack are doing. There are some excellent artists there and in my opinion, to improve you should look at what other folks are doing....taking a class is good for that, feedback from other members of the class can be very useful.