The operation to plant Aya's heart took a few hours. While doing so, Sweat beads always flow across his forehead to his chin.
Having an elemental power himself, he carefully used it. His power was Nature, allowing him to heal wounds.
Also, it gave him precise control of fixing the muscles which were connected to the heart. As well as its blood vessels.
When Kuzu performed the surgery and opened Aya's left chest, he was shocked to see an empty space!
He was shocked that the girl before him had no heart! He almost leaped backward out of fear.
Originally, Kuzu thought that Narukami wanted him to do a simple heart transplant for Aya but didn't expect this patient had no heart, to begin with!
He was also surprised when Narukami grabbed something from his shadow and that something was a heart.
His eyes opened wide when he noticed the heart still beating. This was clearly beyond science to explain!