User blog comment:Hitsuji Mamoru/Servant Creation Room 2 : Guess of the Who/@comment-4802891-20170526200433/@comment-4802891-20170607035159

It's not a vehicle, or even an item he can hold in his hand. Well, in order for you not to think too much about it, it's not something like "Charity" or "Hatred" or even "Soul". It's something that makes him recognizable at first sight tho (I haven't stated in his bio what it is for this reason)