Who is the Mystery Shinigami?

[Madara Byakuya]

I think the mystery shinigami is someone new or someone we know little about.Considering nobody from Soul Society should have interests in ichigo apart from Rukia, but she's quite useless anyway so she wouldnt be of importance in Ishin-Urahara Decissions ?If the Shinigami was someone from Gotei 13 then it would be pointless to hide his appearance, so this means it's a surprise.But still to me they arent related, plain and simple.

This thread is a discussion for some interesting and fun ideas, Shinigami could be anyone, who do you think this is ?

[BlueButterfly139]

Hello!
Personally I think it's Karin, maybe it's just me.
Here's why:
-Karin is hanging around Urahara a lot
-When Urahara went to the soul society people put their reiatsu in the sword right? Well some people who didn't come to help Ichigo put their reiatsu in right? Wouldn't it be easier if Rukia put her reiatsu in at the soul society? And we an tell that the Mystery Shinigami was in the human world because Isshin was there, the doors behind the Mystery Shinigami isn't the senkaimon because the senkaimon's doors squares are smaller and only at the top and middle.