The supporting character's harem is very normal - Chapter 37 Miam!

“You will hear many of his Death Eaters claiming that they are in his confidence, that they alone are close to him, even understand him. They are deluded. Lord Voldemort has never had a friend, nor do I believe that he has ever wanted one,” Dumbledore told Harry Potter with absolute certainty.But what if Voldemort did have a friend? Not just a friend but the friend? A millennia-old wizard, who learned the secret of Hogwarts from the great Four founders, and had his own goals to take over the world?To stop that ancient wizard, an ancient power is called upon . . . in the form of a girl. A Muggle-born at that.Christina Norton has powers beyond anyone's imagination but she is too caught up in the Chosen One Harry Potter's life and catastrophes. But as she starts to uncover the plans of Voldemort, she realizes someone else is working with him. Someone who wants her dead. Why? She doesn't know. She just knows she has to save her loved ones and Hogwarts from Malgino and for that she is ready to go to the end of the world.And fight whoever comes in her way.

A generation's mighty and most powerful expert died mysteriously and reincarnated without any memories on a small planet far away from the Cultivation World.

This small planet was earth.

Five thousand years ago, a great calamity descended on earth. Countless Spatial Cracks appeared in the sky and beasts invaded. After hundreds of years of fighting, humans discovered they could awaken a battle spirit that can help them raise their strength and grant them the abilities that were simply unimaginable for humans before.

Qin Feng also awakens his battle spirit but unfortunately, it was swallowed by his own birthmark, The Infinity Symbol.

This was just the beginning of the mysteries that surrounded him like invisible specks of dust. He soon discovered that the 'Infinity Symbol' was actually not his birthmark but something mysterious from another world.

The Infinity Symbol helped him awaken a Divine Battle Spirit and granted him a Nameless Cultivation Technique that was beyond the world's limit.

He also discovered that he could not die! Every time, he was killed, he returned back in time with the memories of what is going to happen in the future.

Soon after awakening the Divine Battle Spirit, a mysterious beautiful lady stepped into his life and told him that he does not belong to the earth. He was actually the reincarnation of someone called 'KING'.

The mysteries that surrounded him like the invisible specks of dust started to come on the surface from the day of his awakening, revealing many secrets to him.

The reborn Prince Hechingen of the Swabian branch of the Hohenzollern family, sees the situation in Europe, and the war is about to start, so Europe doesn’t wait. Enclosure in East Africa, immigration development, and agricultural foundation, step by step, with the help of the crisis to achieve industrialization.

- Description from novelbuddy

An unnamed 34-year-old Japanese NEET is evicted from his home following his parents' death.

Upon some self-introspection, he concludes that his life was ultimately pointless.

Walking down a street he intercepts a speeding truck heading towards a group of teenagers, in an attempt to do something meaningful for once in his life he manages to pull one of them out of harm's way before getting himself in the way of the truck and dying.

Awakening in a baby's body, he realizes he has been reincarnated in a world of sword and sorcery.

He resolves to become successful in his new life, discarding his past identity for his new life as Rudeus Greyrat.