Pure Magic in Another World

This novel involves the story of a boy on Earth who accidentally dies while trying to save someone but that is not the end, he is reincarnated in Another World called Dorso.
Upon reincarnation another tragedy happens in his life but he is unknown of that until he revealed his magic. His magic type was also unprecedented in history of the whole World.
Then he starts his journey in making a name for himself with his magic but does not reveal his real identity by creating secret identity 'White Knight' but there is someone who knows of this identity.
It's his sister, now what should he do. Threat her, offer her something to stay silent, no he does not but instead he invites his sister to join him in his adventures.
Now let's see how this pair of brother and sister makes whole World shocked by their actions and travels whole World.
But this World seems small after all the travel, then sister why don't we go and roam Another Worlds and Galaxies.