My brother does it to me all the time. It made me wtf, but it's related to the hitbox probably. Also I don't know if it would work if Hakumen is right next to you, but if you do it from the starting range of the match it works. Tager 5B also clashes with it at a certain range which lets you cancel into other stuff.
http://www.dustloop.com/guides/bbcse/hitbox/tager/6B.html
Damn, nice hitbox.