So, can Yujiro be killed?

Is he like a DBZ character? Where bullets don't evne harm him? Or is he just super strong, and super fast, but can still be killed by bullets? If he can why didn't anyone kill him? When they used those tranquilizers, they could have killed him. Why didn't they?

To keep the story going?

That'd be pretty funny, he gets killed like that. They have the perfect opportunity to kill him.

Also, I noticed he was gettin pretty crazy. Me thinks Yujiro was never human, hes a demon taking human form.

Of course he can be killed, it's just not easy. He was felled by snipers armed with tranquillizers when he tried to destroy the Maximum Tournament. Now had he known there were snipers there, it would have been a different story. He's incredibly powerful. But, even he has his limits. We don't really know what he has, but the whole demon thing is just hyperbole. He's been called a "Fierce Lion" as well. . . But, when he's serious, he's known as an Ogre/Oni or a Demon.