Take 5 minutes and 47 seconds out of your day to watch this video.
The first paragraph of the description sums it up:
This guy was hanging out in Yoyogi park in Harajuku, Tokyo, on a Sunday afternoon. He has clearly practiced a lot! I loved the music he played during his performance. My friends and I were completely mesmerized. He has a very expressive face too, with a charming smile… it really sells the show in the end. Made me feel like a little kid.