Korai was kidnapped around his second year of high school and taken to a research facility. Naturally terrified, he tried to escape countless times, but every time he was caught, he was subjected to even more painful experiments.

Then one day, when he turned 20, animal instincts suddenly began to manifest in his body. The project was named 'Beastman'. It was a laboratory that conducted experiments by replacing human DNA with that of animals.

He suffered immensely as his DNA was rewritten.

Eventually, their crimes came to light. The researchers and the facility were investigated, and everyone involved was arrested and imprisoned. However, such punishment didn't bring Korai back to normal, and instead, people even tried to arrest Korai himself.

While living as a fugitive, he encountered Guest, the only person who treated him with kindness. He accepted Guest as his 'Savior' and became gentle and calm only in Guest's presence.