Its Iruka Umino, he picked up Bee' s sword and has it onhis back. That is why the chakra sensing is so wierd. Plus Karin never met Iruka. He finalky made it to where Naruto was to make sure he cane back alive. He found Bee dead and the sword was sad. He pkeaded with it to lend him it's power. So that he can help who is dear to him,Naruto.
Okay maybe not,but it could be Iruka or a Omoi.