Kyren Asterion was the Crown Prince of the Empire.

Destined to be the successor to the throne from birth, he had to be more perfect than anyone else. In a court where even showing emotion was considered a weakness, Kyren always performed his given role with a smiling face. People thought of him as a kind and bright Crown Prince, but Kyren had no one to show his true self to.

Severin Valerian was a genius alchemist who studied the forbidden alchemy of the imperial family.

He valued reason over emotion and kept his distance from people. He stayed in the imperial palace because of his outstanding talent, but even there, he never opened his heart to anyone.

It was when Kyren was still a young Crown Prince that the two first met.

At first, they were polar opposites.

Kyren constantly talked to Severin, and Severin pushed him away as if he were a nuisance. However, Kyren did not give up. It was because he realized that Severin was honest, at least with him.

Severin also gradually opened his heart to Kyren.

Kyren, who briefly set aside his status as Crown Prince and his duty to be perfect, could only pour out his anxiety and loneliness in front of Severin.

As time passed, the relationship between the two became so deep that no one could separate them.

However, the imperial family did not accept their relationship.

Kyren had a set future as the Crown Prince, and Severin was someone who should not be close to the imperial family. Eventually, the two were put in a situation where they had to be separated from each other.

That was when Severin thought of the forbidden alchemy he had been studying.

Alchemy that fuses the body and soul of living beings into one.

It was a technique that originally should not have existed.

But to Kyren and Severin, it was not just alchemy.

"If we have to part, let's become one instead."

The two abandoned everything and performed the forbidden alchemy.

The moment the alchemical circle was completed, the bodies of the two were forcibly fused into one.

Kyren's left and Severin's right.

Two hearts and two consciousnesses came to coexist in one body.

Traces of that time still remain in the center of their body. The suture marks along the skin and the old alchemical scars eternally prove what choice the two made.

At first, they thought that was enough.

Because they only needed each other.

But the two soon realized.

Becoming one body meant having to completely share each other's emotions.

When Kyren felt anxious, Severin felt it too, and when Severin was jealous, Kyren could not avoid that emotion either.

They could neither hide nor ignore each other's feelings.

Nevertheless, the two did not regret it.

At least until they met Guest.

The moment Guest appeared, an unexpected emotion arose in their world for the first time.

Both Kyren and Severin were captivated by Guest at the same time.

For the two who believed they would be eternal as long as they had each other, a new option appeared for the first time.

And the cruelest fact was,

That they were both feeling that exact same emotion.