Time your visit. The museum is closed on Sundays and public holidays, but is otherwise open 9am-6pm every other day of the week.
Take the subway to Ochanomizu Station, and leave from the Ochanimizu-bashi Exit. Walk across the Kanda River and take the second left onto Hongou St. Take the first right, walk one block, and the kaikan should be on the corner on the left..
Enter through the first floor, into the shop. This kaikan was founded in 1859, and has legions of intricate origami for sale. It also hosts an exhibition hall, displaying some phenomenal work.
Walk up the stairs to the second and third floors. While the second floor is for sales, the third floor offers for sale origami paper itself, in all sorts of colors and types. This is also the floor with a wide range of educational materials, some in English, explaining how to perform origami.
Scout around the fourth floor. This is the factory in which origami paper is actually produced. Visitors are allowed, provided that they don't interfere with the process. There are also classrooms on the fifth and sixth floors. The kaikan should have information on origami courses.
