Ragna

Ragna (ラグナ, Raguna) is the main protagonist and one of the titular characters of Ragna Crimson, he was originally a very weak Dragon Hunter who followed the hunter prodigy, Leonica. Not wanting to be a burden for her, Ragna secretly trained so that he could one day protect Leonica instead of her always defending him. However, during one of these sessions, Ragna would not only experience a prophetic dream which told him of a Dragon attack that would lead to the death of Leonica, but he would also gain the power of his future self who'd trained for years to vanquish all Dragons.