Experimenting with the mystic eyes of death perception...

Sora did not experiment with the eyes of death in his early years in the orphanage. He was cautious as he was still wary about the orphanage director. As the director of Kabuto's orphanage was an Anbu.

He was also wary about the cost of using the eye as in Type Moon, a magical circuit is opened in the brain allowing the user to perceive death. And in Naruto, He knew they had chakra similar to the magic in Type moon world. So, he didn't know the consequence of using the death eye without extracting chakra.

(In type moon, Shiki Tohno and Shiki Ryougi have mental strain due to overusing mystic eyes of death. In this fanfic, Chakra will be used as the source of energy to use the death eye as Chakra is the combination of mental and spiritual energy.)

In Naruto to open Sharingan, chakra is required as due to emotional distress, a special chakra in the brain enables Uchiha to open Sharingan. And without chakra, In naruto, people are shown to bleed from the eyes and it puts pressure on the eyes due to lack of chakra.

So, Sora did not experiment with the eyes of death but kept it closed for a long time.

After enrolling on the first day of school, Sora was taught to extract the chakra by the teachers. And after training a few days he was able to extract chakra.

To test the eyes of death, Sora took out a small knife which he took from the orphanage's kitchen which was wrapped in a cloth to prevent harming himself.

With the knife in hand, he cut the line of a small rock. Immediately the stone turned into pieces.

Sora felt a drain of chakra as well as a bit of mental strain. Sora was also a Type-Moon fan and he knows that each death eye is different. His eyes are closer to Shiki Tohno as he perceives the death of concrete physical existences not concepts like Shiki Ryuogi.

As he lived a peaceful past life, Sora thinks of the death of human beings when he thinks of the word death. Due to performing the normally impossible process of his brain classifying the death of non-living objects, it overloads his brain.

If taking the game as an analogy, Sora's death eye is of level one, he can perceive the death of a living being easier than non-living things and is far from understanding the death of concept.

But this will change, as Sora is in the world of ninja where deaths are constant and even he might experience death again, so the more Sora comprehends the death, the more powerful his eyes get.