In Bleach, Shocking Shin'ō Academy

Yu Chen transmigrates into the world of Bleach and becomes a student at Shin'ō Academy, in the same class as Rukia. On his very first day, he shocks everyone. He challenges Tōshirō, and poor little Tōshirō is nearly beaten into a breakdown. From then on, a rumor spreads through the Gotei 13: someone who surpasses Captain-Commander Genryūsai Shigekuni Yamamoto has been born.

Aizen: “Impossible. Why is Kyōka Suigetsu ineffective? And why is even the power of the Hōgyoku so insignificant?”

Yhwach: “Why were the Sternritter wiped out in an instant?”

The Soul King? Sorry, even the very foundation of the world is powerless against Yu Chen.