Maybe a Fake Gintama

Kawaki, hailing from the dragon lineage of a celestial body called Altana, initially encountered Umibozu, a cosmic traveler, and his companion, Kouka. His journey took an unexpected turn when he found himself on Earth, where he crossed paths with a profound teacher, Yoshida Shouyou, who significantly influenced his life. During his time on Earth, Kawaki formed friendships with an eclectic group of individuals. Among them stood out a silver-haired fool with tousled curls, a diminutive man with vibrant purple hair, and a mischievous little devil who famously exclaimed, "Not Zura, it's Katsura!"