What was going on? He could clearly feel both eyes growing, but in reality, they had regressed from the Rinnegan to the One-Tomoe Sharingan.
Uchiha Cheng closed his eyes and tried to activate the Rinnegan. When he opened them again and looked in the mirror, he still saw those purple rings.
The Rinnegan hadn't disappeared.
Uchiha Cheng was baffled, but there was no one who could answer his questions, so he could only investigate and figure things out for himself.
He closed his eyes again and carefully explored the newly awakened power.
With chakra, it was as if a person gained another sense. He could feel the subtle changes in his body more clearly and directly.
Gradually, he figured out what was happening.
His eyes really had grown stronger. He could feel that clearly. But the power of the Sharingan hadn't disappeared; it was real, too.
Through his chakra, he sensed that his One-Tomoe Sharingan was a part of the Rinnegan. Rather than an independent kekkei genkai, it was more like the Rinnegan had gained a new skin.
This was somewhat like Uchiha Madara's situation. Like Madara, he could control his eyes and switch between the Sharingan and the Rinnegan.
The difference was that Uchiha Madara's Rinnegan had evolved step by step from the Sharingan, so it retained the Sharingan's abilities. Uchiha Cheng already had the Rinnegan, but it hadn't yet matured, and its power could only manifest at the One-Tomoe level.
The One-Tomoe Sharingan was simply one stage in the Rinnegan's growth.
Uchiha Cheng's eyes weren't mature Rinnegan transplanted from someone else. He had awakened them himself. Compared with Nagato's mature Rinnegan, his eyes were still only seedlings.
That was also why he couldn't use the Six Paths of Pain's abilities like Nagato could.
Just as all adults had once been children, the Rinnegan had to go through a process of growth. He needed to mature, and so did the Rinnegan.
The One-Tomoe Sharingan marked the Rinnegan's growth from a newborn into an infant. Like a butterfly, it had to pass through a cocoon stage to grow.
Fortunately, his eyes were still the Rinnegan, with an inherently superior nature—a fact confirmed by the Sage of Six Paths. Just as he had awakened the One-Tomoe Sharingan with ease this time, without any stimulus, he wouldn't need to rely on emotional trauma like an ordinary Uchiha to awaken further Sharingan abilities in the future, even the Mangekyō Sharingan. He would only need to provide a large amount of chakra, just as he had this time.
So he would never have to kill a brother or younger sibling.
As he continued to grow, the Rinnegan's power would gradually increase until, in the end, he truly possessed the Rinnegan's full might.
Now that he understood the situation, Uchiha Cheng felt a little dejected. This meant his dream of crushing Shimura Danzō, Uchiha Itachi, and Uchiha Obito on the Night of the Uchiha Massacre was out of reach. If he couldn't escape, he would have to come up with a new way to survive that night.