From what I can see from the pics, looks like Kai can maybe have some boxer, lab mix. Again, it is hard from the pics, but he looks like a wonderful dog.
He looks very a happy and fun guy to have around. I bet he is so much fun. he does look to me to have some greyhound in him possibly, maybe mixed with lab? I have the same problem trying to guess what my dog is, but I think it is fun to try to guess.