Kariya Matou reached out and crawled from the Cold, Damp Insect Nest, numbly shaking out the insects that had burrowed into his ears.
With a push of both hands, he easily hoisted himself onto the platform he had used for support and silently put on the clothes left there.
When he reached the top of the stairs and opened the door to the lavishly decorated living room, Kariya Matou saw that patch of shadow, just as he had expected.
Or rather, the short old man concealed within it.
In the large reception room, the owner's tastes meant there was little furniture beyond the necessary decorations, leaving the spacious room stark and desolate.
There were no lights in the living room. Moonlight was its only illumination, and in that dimness, it was almost impossible to see anything.
But for Kariya Matou, who had already replaced his eyes with sight insects, that posed no difficulty.
"How did you feel today?"
A hoarse voice emerged from the old man's mouth, utterly unlike a human's.
"The same as always. The insects inside me have all been replaced, and the crest worms are in excellent condition."
A year ago, Kariya Matou had returned to the Matou Residence to prepare for the Holy Grail War. Given the Old Worm's twisted tastes, he had expected the old man to subject him to extra torment while improving his capabilities. But to his surprise, beyond the necessary pain, nothing else had happened to him.
He could even say he had become immeasurably stronger than before, both in combat and in magecraft. Although the initial proposal to replace his body with insects, leaving only essential organs such as his brain and heart, had frightened Kariya Matou so badly that he vomited, the results had been a resounding success.
The crest worms supplemented his inferior magic circuits. Transforming his body into an insect nest not only improved his chances of survival but also allowed him to switch familiars whenever the situation demanded. Under these circumstances, simultaneously sustaining a Heroic Spirit with high energy consumption in battle and engaging in magecraft combat was no longer a pipe dream.
According to the Old Worm, this was part of his art of longevity. Were it not necessary to achieve his objective, he would never have wasted such precious materials on Kariya.
Although the price still left him with only one month to live, during that month, Kariya Matou's combat strength would give any mage who underestimated him a nasty surprise.
Given all that, if he set aside conventional sensibilities, accepting the insect nest as part of the workshop was not impossible.
"Could this be the Matou Family's true legacy?"
Recalling the gruesome sight of flesh being devoured by insects that he had witnessed as a child, Kariya Matou felt somewhat puzzled.
"Of course not. How could someone like you comprehend our core legacy, famed for the water decree? Feeding insects with flesh is merely a degraded form of magecraft born of your inadequate aptitude."
At the mention of this, Zouken Matou snorted. "If you worthless descendants had amounted to anything, I would not have needed to adopt a child from the Tohsaka Family."
"Even the heir I originally paid no mind to has become a problem. If I do not find another solution, the Matou Family's bloodline may well die out."
Kariya ignored Zouken Matou's muttering. Although replacing his organs had greatly dulled his emotions, his obsession still burned in his heart.
"Where's Sakura? My modifications are complete. You haven't broken your promise, have you?"
"Of course not. How could I possibly deceive my dear child?" Zouken Matou's gaze settled on Kariya as though he were admiring a work of art worthy of others' praise.
Zouken Matou lightly clapped his hands, and a girl in a purple dress quietly walked in. She possessed a doll-like loveliness beyond her years.
The only blemish was her lifeless eyes, which looked numb and empty, as though she had no soul.
"Sakura!"
Kariya Matou hurried over. His palm split slightly, and a winged insect crawled out, gently circling Sakura Matou once.
"Uncle Kariya..."
The girl named Sakura Matou raised her head. Her eyes tightened slightly at the sight of the insect, but she still answered him.
"Sorry, Sakura. Did I frighten you?"
Kariya Matou wanted to touch Sakura, but remembering his current condition, he silently lowered his hand instead. He let the insect burrow back into his body and sensed the information it brought.
Watching Kariya Matou's ugly display of struggle and anguish, Zouken Matou's lips curved into a strange smile, and he spoke in a voice that sent chills down the spine.
"Well, Kariya? Don't you think coming back a year ago was worthwhile? You saved the Tohsaka Family's daughter before she could be thrown into the Insect Cave. She is exactly as she was a year ago and has never entered the Insect Cave even once. Does that not prove my sincerity?"
"Then why is she like this now?!"
"Honestly, my boy, have you forgotten our agreement?"
Although Zouken Matou addressed him affectionately, his tone held not a trace of warmth, only twisted perversity.
"I would not lay a finger on the Tohsaka Family's daughter. But her surname is Matou now, after all, and she came here as the Matou Family's heir. So I still gave her the necessary instruction about what she needs to know and her current circumstances."
"However, it seems the sheer depth of that terror dealt her mind something of a shock. She has shut herself away and hardly says a word."
"You bastard!"
"You are the bastard, are you not? If you had been a little more useful, the Matou Family would not be in such an awkward position. Even if I really had thrown that girl into the Insect Cave, you would still have to obediently join this war, wouldn't you? So you know what you must do, yes?"
As though asserting his power, Zouken Matou forced a sound filled with revulsion from his throat. At that sound, the insects inside Kariya Matou began squirming with a creaking noise, forcing him to his knees in agony.
"I know. I'll kill that man named Darnic at the first opportunity."
Kariya Matou gritted his teeth, determination settling over his face.
"You had better know. Because the moment you fail, this child will be thrown into the insect nest to undergo the modifications that should have begun a year ago."
"And until then, you won't touch her. Once I kill that man, you'll let Sakura leave the Matou Family, right?"
"I guarantee it."
"Then hurry up. The Holy Relic for Berserker should be ready, shouldn't it?"
To avoid being distracted by any more unnecessary emotion, Kariya Matou hardened his heart, stopped paying attention to Sakura, and headed back toward the Underground Workshop.
"Kariya has grown up, too."
Zouken Matou raised his head with a chuckle and looked at the doll-like little girl beside him.
"Sakura, you have learned autosuggestion, haven't you? Can you activate your magic circuits normally now?"
"Yes, Grandfather."
Sakura Matou answered without emotion.
"Well, the magical energy you produce is not particularly strong, but considering your imaginary numbers attribute, it should be enough to sustain Caster."
A vicious idea took shape in his mind in an instant. Imagining the expression Kariya Matou would wear when the time came, Zouken Matou could not help letting out a wet chuckle.
He was very good at keeping his promises. If he said he would let Sakura Matou leave the Matou Family, then she would leave. He would even fulfill that condition ahead of time.
But he had never said he would hand Sakura Matou over to the Tohsaka Family after she left, had he?
Although he needed Kariya Matou's strength, Zouken Matou believed he had a duty to punish descendants who harbored such childish ideas and imagined themselves benevolent.
"Come out with Grandfather in a couple of days," Zouken Matou said kindly, playing the part of a loving grandfather. "I'll introduce you to a new friend, Sakura. After that, he will be responsible for everything concerning you."
At that, Zouken Matou examined Sakura Matou's fair, lovely hands and gave a cold smile.
"Grandfather guarantees that man will be very fond of you. Only, when the time comes, you may regret not jumping into the insect nest of your own accord."