Maybe a Fake Gintama Novel

Born within Altana's dragon vein, Kawaki embarks on an extraordinary journey when he encounters Umibozu traversing the cosmos alongside his girlfriend Kouka. A fateful arrival on Earth introduces him to Yoshida Shouyou, the transformative mentor who reshapes his destiny. There, he discovers an eccentric band of companions: a silver-haired fool with naturally curly hair, a diminutive purple-haired swordsman, and the spirited character whose declaration echoes—"Not Zura, it's Katsura!" This Gintama fanfiction traces Kawaki's evolution from weakness to strength as he forges unbreakable bonds of friendship, wielding his sword through cosmic wars alongside immortal allies. Not transmigration—pure adventure and camaraderie.