The supporting character's harem is very normal - Chapter 503: This Male Lead Is Too MiserableLaleth Garden.

[STOP STEALING MY WORK, RULATE SITE BASTARDS]Aron died in an underground fight arena, only to wake up in Marvel World with an OP power similar to All For One. But in this world, he is a clone, saved by the X-Men. Follow, Aron's new journey as he tries his best to fit in this world of endless chaos.The biggest question is if he is a clone then where's the original body?[Timeline: AU][Harem> So, please, if you aren't into it, don't read.]...[The cover picture is AI made]...[This is not a translation.]Support link: pat eon.com/UnknownMaster[15+ advance chs] [No double billing]

A young man with an extraordinary mind is off on an exciting adventure when he mysteriously wakes up in the body of a feeble slave-guy in a different, rich in quirks world.

The main character, a selfish jerk, would use extreme means to achieve his goals. However, he never allows his base instincts to overrule his sense of decency. He always pays back both good and bad deeds.

Will his (terrible/excellent) mentality help him make a fresh start? Will he get through misfortunes and hardships of the new world?

When a glorious old civilization was toppled overnight, a strange purple moon rose and thus began the Purple Moon Era.

Damn it! What kind of ecosystem was this? The evolution was messy. Even rabbit bites and plants were not to be messed with. How can one survive all this? Evolve into a Purple Moon Warrior? What did this have to do with the Purple Moon?

What kind of map was this? The Safety Sector? The Floating Domain? The Darkness Port? The Storm Voyage? The True Capital?

The Horror Lullaby List? The resurrection of the Underground Tribe and the prospering Underground City? The Chaos Black Market that suffused the world? The Bloody Road?

More importantly, one could end up in a bloody slaughter when dreaming and enter the Dream Domain? Fine, this damned era!

- Description from Novelupdates

Vincent Strider was a gun for hire who made a living by killing whoever it was his clients wanted dead. But during one mission, he died in a fierce gunfight. However, death was not the end for him. Vincent found himself reincarnated in another world, facing a floating interface that flickered before his eyes.[Synchronizing Host!][Military System initializing.]Vincent found out that in this system he received, he can summon soldiers, tanks, aircrafts, and even warships! This is going to be exhilarating.