10.“The Awakening Of Hyorinmaru! Hitsugaya’s Fierce Fight” Delivers Ice-Cold Power and Frozen Fury In Episode 239, we get to see Hitsugaya’s journey with his Zanpakuto, Hyorinmaru.

One of the first things the audience learns about Hyorinmaru is that it's supposed to be the strongest ice zanpakuto. It is most certainly more powerful than Rukia Kuchiki's Sode no Shirayuki.