Magus Supremacy - Chapter 6: The Watchers

Born of a great family, world shaking genius.

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.

One night she gets drunk and mistakes the most well-known Mafia boss for a host and intends to sleep with him.

Oh my! What should I do? It’s best to run away!

- Description from Novelupdates

After accidentally falling, she actually finds herself bound to a Second Female Lead Counter Attacking System!