Yakou Yukinobu

The wonder child of the Yakou family. A prodigy born in the wrong era. A kind of atavist.
Yukinobu has minimal presence in volume 2 because hiding from the spotlight is what he does every day. Making use of his genius would deprive his whydunnit of its meaning.
As an aside, the Yakou family used Muramasa swords not because of their arcane value but because Muramasa made the most combat-practical katanas. The fact that their arcanity eventually came to surpass their practicality with the passage of the years was a kind of ironic surprise.
Also, his grotesque swordplay resembling a spider is a technique passed down among the Four Demon Hunter Families, not a Yakou tradition.

TYPE-MOON BOOKS material: The Adventures of Lord El-Melloi II Glossary