My Destiny in the Another World: to be the Brave of the Another World.

Nadeshiko Yamato, an unpopular and forgotten high school student, finds a "glorious" death when he's hit by a truck after trying (in vain) to protect a classmate. But his death also marks a new beginning: he is reborn in a fantasy world as Caelan "Cael" de Valenhart, heir to a noble lineage. He discovers a loving and respected family, a circle of loyal friends, and a future far brighter than his previous life. But beyond this "second chance," Cael is soon confronted with a daunting destiny: he is the chosen one, the Chosen Hero, destined to fight the Demon King. The first sign of his power appears when he confronts a dragon in the Dark Ivy Forest: guided by a mysterious mark, Cael reveals extraordinary abilities and asserts his will over the creature. The event draws the attention of the sages of the Sacred Temple, who come to confirm his status as the Chosen Hero and invite him to join their order. But the demons strike sooner than expected. During a surprise attack on the Valenhart castle, the masks fall: Darius, Selia, and Lyra, his family, choose to fight to the end to protect Cael and Theon. In a heartbreaking moment, each says their farewells to the future Chosen Hero. Theon, however, refuses to flee, affirming his love and admiration for his brother by choosing to fight alongside him. Graven, his loyal mentor, manages to take Cael away from the carnage. But this escape comes at a price: Selia, his mother, sacrifices her life, using her ultimate powers as a Holy Priestess to seal the Chosen Hero's aura and protect her son. Devastated, Cael is taken to the Etherhelm Academy, where his true training as a hero will begin. Meanwhile, in the darkness, the Demon King Thal'Kor observes, while his generals bicker and sneer. The holy war has officially begun.