The only thing I'm good at is living long... and I'm the strongest!? ──No, no, isn't this a case of mistaken identity? Alto, a self-proclaimed vampire whose only redeeming quality is his longevity, had lived peacefully withdrawn in his territory for about 2,000 years. Then one day, an invitation arrived── "Lord Alto, the oldest vampire of the Demon King’s Army Four Heavenly Kings. Please attend the executive meeting of the Demon King’s Army. Failure to participate will result in a purge." "Only the name matches!" What he hears from Eleanor, a fellow vampire who came to pick him up, are titles he doesn't remember having and numerous heroic tales... While doubting the mistaken identity, Alto heads to the Demon King’s Castle to avoid being purged. Even though he's just acting normally, for some reason, he is feared and held in high esteem── "If they find out I'm actually weak, won't I be killed...!?" The misunderstanding-based, slapstick fantasy of the strongest pacifist vampire────Begins!!