I’m a Dullahan, Looking for My Head

A games and anime otaku, Kubinashi Sousuke dies from getting hit by a truck, his head severed from the impact. As he accepts his tragic end, he realizes he is in the forest using full body armor.
And when he peeks into the lake, he notices.
“Haa!? Head, why don’t I have a head!?”
He doesn’t have a head.
Sousuke is born again as a Dullahan, but he can’t seem to find it anywhere. Attaching a helmet he picks up as a substitute of his head, and calls himself Duke. Living as an adventurer in the capital, he tries to learn about the world and find his head.
It’s so noisy nowadays because of the friendly fire magician and the self-proclaimed saint.
“Well, you call yourself a saint every day, but you can’t do purification, what a regrettable saint you are.”
“Wait a minute! If you say that much, I will show you the true power of the saint! This’s great, there is an evil presence here, I will prove it by erasing it without a trace.”