User blog comment:RoyalGuard-Elite/Kenpachi Shikai/@comment-9365367-20130914170247/@comment-9365367-20130914214547

Kenpachi's zanpakuto may be on constant shikai but obtaining an asauchi doesn't mean achieving shikai. Shinigami who don't belong to the 13 divisions or the ones who are still in the academy have nameless zanpakuto which do not grant them any power. When they enter in one of the 13 divisions they receive the "official" zanpakuto with an asauchi which they start molding and printing their soul into. Only after a slow training with the oficial zanpakuto shikai is achieved.