Throne of the Ghost Emperor (Danny Phantom X Naruto) - Chapter 12

When a struggling graduating student failed his capstone project, he got frustrated and attempted to take his own life. The moment he was about to take a leap, a voice stopped him and handed him a strange box and disappeared.As he got home, he opened the box and saw a strange usb device and a set of strange pills. Later he found out that the USB contained inventions from the 20th to 23rd century, and the pills were a nootopic drug.With this discovery, his life would soon change from an outcast of the family to the world’s powerful businessman that would create companies that would rival top companies around the world.

The Apocalypse is in full swing. Defiled - powerful creatures corrupted by the Great Collision - prowled the lands in search of prey. Unfortunately for them, the human race had long since retreated behind the secure walls of the Sanctuary of Everlast. During one of his regular excursions outside the Sanctuary, Alden is separated from Celeste. - his childhood friend and crush. In that moment, he came to regret never summoning the courage to confess. Somehow managing to survive thanks to some trickery, Alden awakens as a mage. Instead of receiving a normal power, he gains the ability to decay. What’s more, during his ascension, he received a vision from his future self advising him not to trust the Asterons - celestial beings who had saved his race from inescapable doom. Normally... such a revelation wouldn’t faze Alden. However, there was only one major problem with the declaration, though. Celeste was bound with an Asteron. And not just any normal Asteron... She had made a pact with one of the Divine Sovereigns.

[Host, host, I am the System, I can help you conquer the world and the witches with various personalities.]Xi Mu: Hmm... Isn't this an action game? When do we start slashing?[Right... This is an action game, but I suggest that the host also try to seduce the witches along the way, there are generous rewards.]Xi Mu: What rewards?[Of course, the perfect romantic experience!]Xi Mu: No need, I've already played through the romance plotlines. Now I just want to go on a rampage and speedrun the game.][...]

In a romance novel called “The Secret Lovers of the Academy” the male lead would often torment his fiancée–but wait, why did she cross into this world to become his fiancée, the villainess, instead of the heroine?