Books Kinokuniya is a book and stationary store located inside Mitsuwa Marketplace. If you walk into Mitsuwa and make a right you will run into the store. Upon entering, you make a left and another left, it is tucked away in the corner of the book store.
For fountain pens, they stock Pilot, Platinum, Lamy, Ohto, J. Herbin and a couple other brands.
For inks, they carry a lot of J. Herbin and Iroshizuku bottles. I also saw cartridges for Namiki/Pilot, Platinum and Ohto.
They also stock a lot of good stationary paper/journals by Moleskine, Rhodia, J. Herbin and a couple other brands.
There are 2 older Japanese ladies that run the small desk collection there, although they speak very limited English, they understood the basics of what I was looking for and when I wanted to test out some of the available fountain pens there.
I picked up a Pilot Cavalier here for $45. Pricing is between below-average to average MSRP. Great little store and friendly staff.