A brief description of the manga Eternal Youth:
Roberta, a priest of the Public Church, is assigned as the head priest of Dietmarschen — a remote backwater at the far northern edge of the world. The position is handed to her immediately after her predecessor mysteriously disappears, so Roberta approaches her new post with wariness and begins to quietly investigate the Duke of Dietmarschen, Ulrich. By all accounts, he has held his lordship for over 300 years. And by his own admission, he is an immortal — one who has lived a life no ordinary human could ever know.
