After Ren had caught that little wimp named Taka. He walked back to his office where he glanced inside. Ryuu was still there.
He searched eye contact with him and 'said' that this wasn't over yet.
And he continued to drag Taka with him, without any mercy, to the ER (Emergency Room).

And so he left Ryuu behind and he wondered what Ryuu would do next. 
Would he follow him, or go home?