Kishibe
If you consider that Kishibe is the one who trains other strong characters like Power and Denji, you have a good idea of how formidable he is. Kishibe is quiet and stoic, yet when it comes to killing demons, he is merciless. Kishibe is a powerful Devil Hunter since he has spent years killing demons.
There is no one who can match Kishibe physically. In one episode, he used a single punch to shatter a weapon forged from Power's cooled blood. Kishibe's superhuman talents make him a nightmare for the demons. Kashibe is currently in touch with the Claw Devil, the Knife Devil, and the Needle Devil.