My lesser doesn't have Bushido on the menu either.
BUT... it did have bladeweave... and when I selected that it said I needed Bushido 500. I'm like ok... so I added it and it cost 600 (100 for the bladeweave and 500 for bushido)
Now my lesser has bushido.
Wish I had have looked to see if whirlwind was on there though before selecting bladeweave.
But now of course I cannot add any other abilities to it.... nm