When I first saw one of these in action in the City Hunter 2 TV series I really wanted to do an entry on it.
soba-giri bōchō 蕎麦切包丁
But try to find good information on a specialized knife for making soba in English!
Luckily many years later Nozaki Hiromitsu's book Japanese Kitchen Knives is published and has two pages on the mighty blade! OK so one page is a picture, but that photo is worth plenty.