Type-Moon: Star Redemption of Arthur Pendragon

He is the King of the Stars of Britain, the boy who witnessed countless tragedies when he pulled the sword from the stone.
Arthur Pendragon, at the age of fifteen, his fate deviated from all the "predestined" paths.
The sword in the stone brought him not only the throne, but also the "Trajectory of the Stars"—the power to travel through parallel worlds and glimpse countless possibilities.
He saw Camelot's flames, the shattered round table, his best friend's betrayal, and his sister's tears.
He also saw another "self" raising a sword in the ruins of Fuyuki City, saw the end of humanity burning down, and saw the lament of the True Ancestor and the Dead Apostles under the moon.
"If the inevitable tragedy cannot be changed, why become king?"
His answer was—then change what is "destined".
He became an apprentice of Scáthach, the Queen of the Land of Shadows, and learned to sever the spear of fate.
From enemies to allies with the witch Morgan le Fay, healing a thousand-year-old grudge.
In Avalon, they meet the fairy Meli, who has been waiting for them for a thousand years. She is cunning and sharp-tongued, but hides her loneliness in her smile.
Travel through the Fourth and Fifth Holy Grail Wars to save the weeping girl.
Step into the Babylonian monster front and fight alongside the goddess Ereshkigal.
This is not a story of a king conquering the world.
This is the story of a "person" who learned to save others—and then gently and firmly pulled those who should have fallen into the abyss back to the light, one by one.
"My sword will not slay the innocent."
My path exists solely for redemption.