I Changed Type-Moon History

Tang Ping inherited his family's island in the middle of a lake. Strange guests kept showing up there. "Could you be the legendary lake fairy?" "I am the emperor of Rome! Why would I ever kill myself?" "So I was going about seeking immortality the wrong way!" He helped King Arthur change her fate, advised Nero on strengthening Rome, and guided the Qin Empire toward a legacy lasting a thousand generations... Before long, Tang Ping had acquired a string of widely known titles: King Arthur's mentor, the accomplice of the tyrant Nero, the immortal master of the Qin Empire...