I got this last time I went to japan, it's ranked #1 by 信長書店, a large chain adult shop in Osaka and Kyoto. The bumps are nice, the twisting zig zag channel wraps around tightly and doesn't let air escape. This combined with the large vacuum chamber at the end, you can squeeze out a lot of air and create a nice suction. I could only find a few english review, not sure why its not popular here