Chapter 1: The Man Who Fought His Way Backwards Through the Dungeon!
The beginning of the story originates from the pitch-black depths of the dungeon.
"Where... is this place?"
Emiya Shirou opened his eyes, looking around in confusion.
A pitch-dark and mysterious labyrinth, with mutated plants occasionally emitting faint glows, and within the shadows lurked unseen dungeon monsters, silently observing him from the darkness.
In such a bizarre place, fragile humans were destined to become prey—devoured alive by monsters hidden in the shadows, turned into fertilizer for the Dungeon.
Yet Emiya Shirou did not feel fear.
He felt more confused—unable to understand why he had appeared in such an unfamiliar place.
In his memory, the last thing he recalled was engaging in a final confrontation with the Ainsworth family to save his younger sister, Miyu.
In that battle, which had reached its peak intensity, he slew six opposing Heroic Spirits in one night, bringing an end to the Holy Grail War.
Then, using the Great Holy Grail's power, he transferred Miyu to another world to protect her— and encountered Ainsworth's final trump card: Angelica.
The woman named Angelica could use the card of the strongest Heroic Spirit—Gilgamesh. Once possessed, she essentially wielded all the power of Heroic Spirit Gilgamesh.
Shirou was no match for Angelica and was ultimately defeated.
But just as he was about to be captured, he clearly saw that the Great Holy Grail, which had nearly lost its glow, suddenly activated again—seemingly in response to his wish.
As the Great Holy Grail's light erupted, Shirou came to and found himself in this unfamiliar dark Dungeon place.
"Could it be... the Holy Grail fulfilled my wish?"
Shirou stared blankly at his surroundings, his heart filled with indescribable complexity.
Because he still remembered clearly the final wish he made— To obtain the power to protect his sister Miyu, to protect all the people important to him, and to overturn all tragedies.
If that wish had indeed come true, then in what form did the Grail choose to realize it?
Shirou's mind was filled with complicated thoughts. He couldn't imagine what kind of place he had been brought to.
At the same time, even as Shirou was immersed in his thoughts and confusion, the monsters deep within the labyrinth weren't going to give him any extra time.
Upon sensing that Shirou didn't seem aggressive and appeared to be a "fragile" ordinary human, the monsters decisively charged at him.
Yet Shirou's expression did not show the slightest panic.
He calmly assessed the situation, and the moment the monsters were about to rush him, he softly murmured—
"Trace On."
With a flash of light, two uniquely shaped twin blades appeared in Shirou's hands.
One black, one white- the "married" twin swords.
Shirou effortlessly swung the twin blades, blocking the monsters' assault with swift movements, and in a counter-strike, pierced through the monster attacking him.
"Although I don't know where this place is, it looks like I can still use Projection. The projection of Kanshou and Bakuya isn't affected. The mana flow is normal, no issues…"
Shirou muttered to himself, retracting the twin blades in his hands.
This was his unique skill: the magic of Projection, capable of creating replicas of original items.
However, ordinary people couldn't project to this level.
They couldn't do it so quickly, nor could they create projections almost identical to the originals.
Shirou's ability came from his own special nature—partly due to possessing the powers of a Heroic Spirit.
Of course, that topic need not be explained in detail for now.
For now, the most important thing for Emiya Shirou was to figure out where he was, and how to leave this pitch-black Dungeon and reach a place where humans lived.
After slaying the monster, Shirou initially wanted to inspect the corpse to figure out what kind of place this was.
But unexpectedly, the monster disintegrated into ash right after dying, as if it had never existed.
On the spot where the monster had perished, only a strange gray-black stone remained on the ground, emitting an eerie glow.
"This is...?"
Shirou picked up the gray-black stone and inspected it, but found nothing of value. Helpless, he discarded it and officially began his exploration of the Dungeon labyrinth.
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The Dungeon was a place full of danger.
After several days of exploration, Shirou became especially certain of this.
Everywhere he went, he encountered all kinds of unique monsters—some resembled beasts, others looked like familiars, and some were simply indescribable…
Faced with such dangers, Shirou had no choice but to seriously study each type of monster, learn their habits, and then conduct targeted hunts.
Fortunately, Shirou's combat ability far surpassed that of ordinary monsters. One-on-one, he could easily slay them.
Even when packs of beast-like monsters attacked, Shirou had nothing to fear. He would project bows and arrows, maintain distance, and pick them off one by one.
During this process, Shirou noticed that over time, his body seemed to be undergoing some form of growth.
His speed increased, his strength improved, and even some fundamental aspects of his being had subtly changed.
However, because the changes were so gradual, Shirou didn't pay too much attention to them.
There was another issue with Dungeon life: food and water.
Surprisingly, water was not a problem. Even though it was underground, he often found rivers with inexplicably clear water—so pure it seemed otherworldly.
Food was also manageable.
Thanks to Shirou's excellent cooking skills, he was able to make meals using roadside plants, keeping himself nourished and active.
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One day, as Shirou was nearing the end of his exploration in one area, he unexpectedly discovered a staircase spiraling upward.
The staircase was narrow and ancient, as if no one had ever reached it before.
Confused, Shirou stepped up the stairs, eventually arriving at a strange room.
The room was vast and completely empty.
But the moment Shirou stepped into it, a terrifying monster several dozen meters tall suddenly descended from above and attacked without warning.
Faced with such a terrifying presence, Shirou dared not be careless and fought with all his might.
Using his Projection ability and all the experience he had accumulated battling monsters, Shirou successfully slew the powerful monster.
As the boss died, a stream of strange energy flowed from its body into Shirou's.
After absorbing this energy, Shirou could clearly feel a notable enhancement in his physical attributes—his speed and strength had noticeably improved.
This was a far greater boost than anything he had gained from killing regular monsters.
'Could this be the reason the Holy Grail brought me here?'
Shirou was stunned, and continued his exploration of the Dungeon world.
He discovered that this world seemed to be structured in floors, each with distinct terrain and ruled by a unique floor boss.
As he climbed further upward, Shirou occasionally encountered "humans."
However, calling them human was a stretch—there were beast-eared and tailed people, elf-like beings from stories, and even lifeforms that looked monstrous.
Naturally, Shirou wanted to communicate with them, hoping for some interaction.
But they were extremely wary of someone like Shirou, who roamed the dungeon alone.
More often than not, battle would erupt before any conversation could even begin.
After several meaningless fights, Shirou had no choice but to abandon attempts at communication and resume his solitary dungeon conquest.
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After slaying around a dozen monsters, Shirou began to notice something: the dungeon monsters were getting weaker.
With the monsters growing weaker, the gains he received from killing them also diminished.
Originally, he could feel a drastic improvement after killing a strong monster, but now, even slaying a powerful one yielded no more than the same result as killing a common monster.
From this, Shirou inferred that the dungeon had a hierarchy.
The stronger monsters were located in deeper layers, offering greater rewards when defeated. Conversely, weaker monsters were in higher, shallower levels and gave lesser rewards.
Based on this, Shirou realized that he must have been transported to the deepest part of the dungeon from the start—and his journey had been a reverse crawl, steadily approaching the dungeon's exit.
With this understanding, Shirou naturally wanted to escape this sunless place.
He didn't want to be trapped here forever.
However, perhaps due to the countless battles he had endured, or the lasting injuries from his fight with Angelica that had never healed...
As Shirou tried to leave the Dungeon, his movements became increasingly difficult. The strain on his body made it hard even to walk normally.
He was nearly dragging his battered body toward the surface.
If he avoided unnecessary actions and got lucky, perhaps he could reach the surface before his body gave out.
Perhaps.
But to Shirou, the most important thing now was not to waste energy on anything unnecessary.
Doing so might cause his already near-broken body to collapse completely.
That was exactly what he intended to do—take no extra actions until reaching the surface.
Until, suddenly, a scream rang out from the distance—
"Help! Help meeeeee!!!"
Hearing that desperate cry from a young boy, Shirou's nearly overburdened body moved almost on instinct.
He ignored all rational thought, disregarded his body's warning signals from overload—
Shirou acted purely on instinct.
Because deep within his heart, under the seemingly extinguished flame of passion, he had never forgotten that ideal from so many years ago—
To become a hero of justice!