While sealing the forbidden rift, Naruto kept his whole body tense, constantly sensing every change around him. He remained on guard until the sealing was complete, only then allowing himself to relax.
Although staying alert was a basic requirement for a ninja, Naruto had never been this vigilant. He had always been carefree, with none of the wariness a ninja ought to have. Others might not have noticed his sudden caution, but Sasuke, who had grown up with him, saw the change clearly.
Only after the sealing ended did Naruto relax a little. This worried Sasuke, who wondered what had happened to him. What could possibly have made someone as carefree as Naruto feel threatened? But this was not the time to ask, so Sasuke could only suppress his curiosity. After all, the Tree of Life was still here, and obtaining the Life Flame and the Life Gem was their top priority.
After they successfully sealed the forbidden rift, the Tree of Life honored its promise and gave Naruto and Sasuke the Life Flame and the Life Crystal.
That was not all. The Tree of Life also brought out another crystal. The sight immediately caught Naruto and Sasuke's attention, and Naruto asked curiously, "What's this?"
The crystal the Tree of Life had produced drew all of Naruto and Sasuke's attention. Neither noticed that the little fox on Naruto's shoulder had fixed its gaze on the crystal the instant it appeared. Only when Naruto and Sasuke came back to their senses did Little White Fox realize it had unwittingly given itself away, and it hurriedly returned to its earlier demeanor.
Naruto asked in confusion, "Isn't this a Power Crystal?"
The Tree of Life said, "Yes, this is the Demon Beast clan's Power Crystal. In fact, one of my children gave me