Japan is heaven for a cartoonist because you can buy any supplies you want almost anywhere. I LOVE "stationery stores" (bunboguten), especially the small gramma-and-grandpop ones with lots of really old stuff, like ancient protractors and drafting guides and dip pens with years-old price tags. I stop at EVERY bunboguten I see because you never know what you might find. Here are some pics of the stores I frequent.
A small joint near my school in Kobe, where I recently blew 6000 yen on Gocco supplies discounted to 20%! You do the math...
Whole lotta pens
A fancier shop that sells a lot of European brands.
I would have bought this word-balloon template for the novelty if it wasn't so expensive. It's also really small.
I'm always keeping tabs on whether anyone else is buying this stuff. I think nobody does.
You can see a small stand of screentone pages! I love flipping through them. My favorite ones are tacky, over-rendered backgrounds.
Interesting tin pencil sharpeners
Attention Sam Gaskin, get your white-out of choice here. There's also tons of pen nibs.
A variety of fun stuff.
Trace your lettering in English, Japanese, numerals, wingdings, numerals, italics...
I just love all this stuff!