Naruto and Kallet fought in the most primitive way possible: with taijutsu attacks, without even using chakra or demonic energy. Because of their respective physiques and pupil techniques, both had abandoned those powers.
Whether demonic energy or chakra, using it was like throwing meat to a dog-it was never coming back. After several ninjutsu and demonic energy attacks, both had independently given up. Naruto had tried attacking Kallet with Wind Release: Rasenshuriken, but it had failed to inflict any real damage on his body. Instead, thanks to his Light-Dark Body, Kallet had absorbed Naruto's Wind Release: Rasenshuriken and converted it into demonic energy.
Kallet had done the same. He had tried a demonic energy attack, Black Dragon Energy Burst, only for Naruto to absorb it with the Rinnegan's Preta Path, so he had given up as well. Both had realized that, aside from taijutsu, their other supernatural attacks could not hurt their opponent at all and would only strengthen him. As a result, neither used ninjutsu or demonic energy anymore.
Kallet could now use his Light-Dark Body to match Naruto in taijutsu, while Naruto could only fight him using the White Eye's chakra control and the Rinnegan's Asura Path. That left neither able to finish the battle quickly. They could only keep trading blows and wearing each other down.
Although it was a battle of attrition, their clash was extraordinarily fierce. Naruto had the advantage of the Flying Thunder God Technique, which let him teleport at any moment and dodge or attack with incredible speed. Kallet, on the other hand, had extensive experience, and his reactions and attacks were many times faster than Naruto's.
The instant Naruto teleported behind Kallet, before he could even attack, Kallet sensed him. Before Naruto made his move, Kallet had already turned around, ready to