The bizarre six-tomoe Sharingan was Uchiha Tsuki's Eternal Mangekyō Sharingan!
When Uchiha Tsuki appeared before Shimura Danzō and awakened those Eternal Mangekyō Sharingan, Danzō felt as though the entire world had turned red. For a moment, he could not even tell whether he was trapped in a genjutsu or standing in reality.
However, Uchiha Tsuki could clearly tell Shimura Danzō that he was actually in a world between reality and illusion.
It was also the world of Uchiha Tsuki's Eternal Mangekyō Sharingan.
When Uchiha Tsuki awakened his Eternal Mangekyō Sharingan once more, his strength had already been weakened during the previous battle, leaving his control over the Eternal Mangekyō Sharingan's power extremely frail. Thus, when Uchiha Tsuki used his Eternal Mangekyō Sharingan to cast a genjutsu on Shimura Danzō, a scene that even surprised him appeared. After awakening the Eternal Mangekyō Sharingan, he discovered that he and Shimura Danzō had entered a strange world.
It was the boundary between Uchiha Tsuki's genjutsu and the real world.
If Uchiha Tsuki exerted himself a little more, Shimura Danzō would enter the genjutsu. But if Uchiha Tsuki relaxed even slightly, the chakra he had just spent would be wasted. The Eternal Mangekyō Sharingan genjutsu he had expended chakra to use would simply fail to take effect.
In other words, it was a world half illusion and half reality. How that world would ultimately be shaped depended entirely on Uchiha Tsuki himself.
As for Shimura Danzō, after Uchiha Tsuki cast that incomplete genjutsu, he immediately became vigilant. Danzō could never forget how arrogant Uchiha Tsuki had been back in Konoha. Now, facing Uchiha Tsuki once again, Shimura Danzō truly felt the shadow of death hanging over him.
Then, as the colors in Shimura Danzō's eyes all turned red, he formed hand seals directly before