Strange Tales of Heian-kyo

Also known as IF Fantasy: The Genderbent Angel's Wondrous Adventure

Let me tell you a secret: I have an invincible System, and it can even help me fight. Wait, System, I'm your master! I'm warning you, don't do anything reckless!

And so begins the otherworldly adventure of a not-so-bright young man (or woman) and an invincible System~!