This might sound weird but I actually learned to ride a bike on those little pocket bikes lol. I'm a small girl so it wasn't too bad. And it was manual which is also a good help to learning. But like the previous person said, taking a bike course is good too. If you're under 18 take advantage of it, you pay less. Once I hit 21 I had to pay like $200. Hope this helps.
If you want to learn to ride a Busa you might as well start on the GSXR 600/750. Plus they use the same technoligy and its close to the same foward lean design, just on a smaller frame.
If your looking to learn quickly you might outgrow anything thats smaller to fast.