User blog comment:Xilinoc/Ch. 571 (Yachiru's gonna wreck it)/@comment-26420452-20140305103542/@comment-5398287-20140305230247

I would imagine he might be talking to his Zanpakuto, actually. He started wanting to know about it after he realized how it shared the pain of not having a name (figuratively, of course, since it had one but he didn't know it.