Low-Man Divinator

[Shirai]

I'd say the easiest would be The Warrior's Path II, the Tenzen BCNM.
With a Zerg setup of decently geared melee you should be able to clear Difficult without 1 hours quite easy.

/nin is the best sub for this fight (including your healer), and remember not to Weapon skill when is Yaegasumi is up, because otherwise he will rip your party apart.
Oh, and a well equiped bard to sleep the Tarus would be recommendable too.