Lore:
Shirou Emiya, Sole survivor of Fuyuki's Great Fire, Adopted Son of Emiya Kiritsugu, The Magus Killer, Master of Saber in the Fifth Holy Grail War, a man with the wish of being a Hero of Justice being his main motivation, the desire to save other people's live's as a mean of attaining happiness due to his own distortion making him unable to do so by normal means, a man whose Origin and Element are both "Sword" making him only a third-rate magus at best for all his life. After the events of the Fifth Holy Grail War he went with his teacher/lover Rin Tohsaka to the Clocktower, where he was belittled due to his unability of using magecraft "Like a decent magus should". Using all the knowledge he gained of his own magecraft during the War after witneesing and making his his future's self abilities, he started studying and training to master them, saving and helping people every time he could, entering combat after combat, conflict after conflict, war after war, watching the worst side of humanity and still marching towards his own ideal of being a hero without regrets or fear, with every combat more experience, with every year more skill, with his lover never leaving him behind. year after year, his fame grew, just like his power and domain over his Reality Marble, after a decade he attained the ability to "Imprint something's existence atop other", in individual's objects, but that wasnt enough, it was a powerful ability, thats for sure, but he needed more, he needed to use it with Noble Phantasm, he needed to be overwhelming, and so he started the process of perfecting his newly discovered ability, constant failure, constant fighting, constant loving, constant trying, and at some point, he achieved it, the power to overwrite an object's existence, and with that, the power to manifest his Reality Marble in individual objects, starting from his body, to manifesting it in swords.
The man known as Shirou Emiya never rested, but he was glad to do what he did, even in his dying moments, he had a smile on his face, having a family, living with his beloved wife, the last thoughts in his mind were "I told you i wouldn't have any regrets, Red Jerk", before closing his eyes for the last time and entering the Throne of Heroes, overwriting his other self's existance as part of the counter guardians and turning him in another "Version" of him, the Heroic Spirit Shirou Emiya, giving him the rest he deserved after a eternity of fighting and killing.
He was a Hero of Justice even at the very end, and his path, despite being hard, was one he enjoyed.