I’m a Dullahan, Looking for My Head

A games and anime otaku, Kubinashi Munesuke 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 a full body armor.
And when he peeks into the lake, he notices.
“Haa!? Head, why I don’t have a head!?”
He doesn’t have a head.
Munesuke is born again as Dullahan, but he doesn’t have his head anywhere. Attaching a helmet he picks up as a substitute of his head, he calls himself Duke. Living as an adventurer in the capital, he tries to learn about this world and find his head.
It’s so noisy nowaday because of the friendly fire magician and the self-proclaimed saint.
“Well, you call yourself 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 power of saint! This’s great, there is an evil presence here, I will prove it by erasing it without a trace.”