User blog comment:Apocaylpse06/Ichigo Kurosaki's (New) Zanpakuto/@comment-3393030-20110817034524/@comment-4484409-20120509160209

Yeah you do have to know the name of your Zanpakuto to use Shikai, the only exception being Kenpachi whose overwhelming Reiatsu makes it impossible to seal his sword. Hinamori does say Toubiume when releasing her shikai or its power.