I, Uchiha Isami, Am Not Hated!

Water Hashira Giyu Tomioka thought his story ended with Muzan's death—until he wakes up as Sasuke Uchiha's twin brother in the shinobi world. All he wants is a quiet life protecting his new family, but fate has other plans. On his fifth birthday, a mysterious system awakens, forcing him into proximity with his clan's prodigy, Itachi. Every hour spent near powerful shinobi unlocks breathing techniques from his past life. As the Uchiha massacre looms and hidden agendas swirl around him, this reluctant hero must decide: can he change destiny without becoming what he once fought against?