Returned to the Past, the Hero is Protected by the Villain?

In this world that is similar to our own, the Empire of Exodus houses one of the strongest guilds in the current world, Exol. It's job is to close rifts that could allow monsters to run rampant.

People who can close these gates are called the 'Reincarnated'

The Villain of the story would be Deus Manachi

He is the number one of the Exol guild, and one of the leaders that closed the the first main gates during the time of crisis.

Although seemingly a hero, he was cold, cruel, and merciless. Killing anything and anyone that stood in his way.

He was cynical and practical.

Everything he did was in the name of protecting everyone and if some people had to be sacrificed for the greater good, it would be their honor to serve the empire and protect their families with their lives.

However, for a villain to exist, there needs to be a hero. He would be Hiiro Seraphim.

Coming out of seemingly nowhere, he rose in fame and prestige. He cleared rifts solo and didn't sacrifice anyone, and protected anyone that needed to be protected.

As two opposites would attract, they would always end up in oppositions with one another.

As their last fight happened, with destruction around them, the villain drew his last breath as his heart was pierced by the hero's sword.

However, as he wandered through time with a spiritual body, unable to ascend, he slowly saw how the hero helped the people and accomplished what he had thrown his life and morality away for.

Realizing how much pain he had caused he let go of his remaining attachments to the world, letting the hero have his happy ending.

However, fate seems to have its own plans for him.

He woke up to a familiar ceiling. Looking at himself, years younger.

"It seems I've turned back to the past..."

Rather than cause pain for the people I wanted to protect, this time I'll support the hero from the shadows.

However... the hero seems to be acting strange?

It seems like the villain will have to protect the hero for now.