The Rising of the Shield Hero (2019)

Iwatani Naofumi, an ordinary otaku, stumbles upon a mysterious book that transports him to a fantastical realm. There, he becomes one of the Four Cardinal Heroes, tasked with battling the devastating Waves of Catastrophe as the Shield Hero. Initially thrilled by the adventure, Naofumi's excitement turns to despair when he faces betrayal, leaving him stripped of wealth, honor, and trust. Forced to rely on a slave named Raphtalia, he must confront the Waves and navigate this treacherous world. Can he reclaim his dignity and alter his dire fate?