Shinji's concern was no baseless worry.
Not long ago, he had seen with his own eyes how the "biological exoskeleton" had practically hijacked Neji and taken him toward the moon. He didn't know whether it had been drawn to the Giant Tenseigan on the moon or had been controlled and bewitched by it.
After all, any puppet whose sentience had been awakened by Tenseigan Chakra would obey the Tenseigan unconditionally!
Shinji knew just how much this Fusion State could boost their combat strength.
Their Chakra and concentration doubled, they could perform Hand Seals twice as fast, and so on. As long as Neji and Kimimaro could develop good teamwork, their strength after fusing would at least double.
But if the sentient "biological exoskeleton" was drawn to or controlled by the Giant Tenseigan on the moon—and the exoskeleton had more control over them than they did over it—then the stronger they became after fusing, the more disastrous it would be for Shinji!
"Whatever happens, we mustn't let the 'biological exoskeleton' go out of control."
Shinji made up his mind.
If the "biological exoskeleton" went out of control, Neji and Kimimaro might lose their autonomy, and his "Tenseigan Plan" would fail completely.
So Shinji stopped Neji and Kimimaro, who were still getting used to the Fusion State, and instructed them, "Try to see if you can undo this Fusion State!"
"Yes!"
Neji and Kimimaro stopped exploring the fusion's capabilities and tried to undo it.
After a few attempts, the "biological exoskeleton" binding them together suddenly split down the middle. Each half shrank back onto one of them, returning to its sealed state.
As the Fusion State ended, Neji and Kimimaro both staggered. Kimimaro even dropped to one knee and began panting heavily.
Shinji asked, "What's wrong?"
Kimimaro shook his head. "My Bloodline