A dark basement, damp walls, an abnormally disgusting environment.

A grotesque, emaciated old man is laughing, harboring a dark delight, pleasurable, stomach-turning smile.

Insects, insects, insects, insects, insects, insects.

Insects are everywhere.

Eggs, larvae, pupae, and adults.

Squirming, crawling, and flying.

Densely packed, a swarm of insects more nauseating than the old man's smile, flooded towards the trembling girl huddled in the corner.

She was still a girl in kindergarten, with short black hair reaching her ears and gem-like big eyes. She is a girl who evokes pity in the hearts of most people but not in the heart of the owner of the basement, the old man who shares the same space with the girl.

The old man ignores the girl's cries and pleas and drives the swarm of insects closer to her, laughing manically.

"Come, Sakura, only this way can you become a member of the Matou family, my true granddaughter."

At this point, the girl can no longer hear what the old man is saying. Her heart is filled with immense fear and she curls up in the corner, trembling. From her quivering lips, whispers that she can occasionally hear escape.

"Father..."

"Mother..."

"Sister..."

"Save me..."

However, her voice is not audible to the old man, who continues to laugh uncontrollably, let alone to the person she is calling.

"Anyone..."

The swarm of insects draws near, just a hair's breadth away, from the girl's delicate skin. In her dim eyes, she could see the insects with their liquid-filled mouthparts and segmented limbs.

Instinctively, the girl closes her eyes and lets out a desperate cry.

"Somebody... Save me."

Perhaps Gaia did not wish to witness the loss of brilliance in the girl's nascent life, or perhaps Alaya unconsciously felt a pang of compassion, or perhaps there was a slight shift in the world before the quantum fixed band.

The forcefully sealed door of the basement, a place that no one wants to approach and no one dares to approach, is kicked open with great force. A breathtaking light cuts through the dimness, slicing through the girl's fear, and the swarm of insects that fills her vision.

A youthful but sunshine voice is found in the ears of the girl.

"It's alright, I'm here, big brother is here to protect you."

The girl opens her eyes just a slit and hazily sees a boy slightly older than her standing in front of her. He has short, naturally curly purple hair, a not-so-tall but upright figure, and an aura that stands in stark contrast to the surroundings.

The girl recognizes the boy, the one who always follows the man called "Father," whose name is "Byakuya Matou." He is the person she should call "big brother."

The girl inexplicably recalls the scene a few hours ago, when they first met.

"I'm Shinji Matou. You must be Sakura. From today onwards, you're my little sister, and I'm your big brother."

"Bi... Big brother." The shy girl lowers her head and timidly utters this unfamiliar address like a delicate young deer.

The boy squats down on the ground and his bright smile meets the girl's evasive gaze. "Hmm, from now on, Big Brother will protect you."

At that time, the girl did not take it to the heart, but now she believed it.

Leaving behind her warm family—her father, mother, and sister—she arrived in an unfamiliar environment, changing her surname from "Tohsaka" to "Matou." A sense of confusion filled the heart of the girl.

While the girl was sitting in her new room, lost in thought after finishing dinner, Matou Zouken, the head of the Matou family, and the one she should call "grandfather," brought her to an uncomfortable basement.

Nightmares began soon.

The one who shattered the nightmare was her brother, who claimed to protect her from their first meeting.

Standing opposite her brother, Zouken Matou, immersed in a sea of insects, was filled with anger and astonishment.

He was angry that the ritual was interrupted before it even started and astonished that the one who interrupted the ritual was his ordinary, talentless, seemingly useless grandson.

"Shinji, what are you doing here? I believe I've mentioned that nobody is allowed in here." The old man's small eyes narrowed into slits, resembling insect eyes more than human eyes, as his pupils focused on the door that Shinji kicked open–the man who should have been guarding it was now nowhere to be found.

"Don't bother looking; my father has already been taken care of by uncle," Shinji calmly said.

"Uncle?" Zouken's face wrinkled, a shadow of unease appearing in his heart. "Kariya? That worthless family deserter? How could he...?"

"Uncle has returned. Just a moment ago, " Shinji's tone carried a hint of mockery. "—brought back by me. Are you surprised?"

"You?" Zouken's pupils had contracted. It was the second time he looked directly at his grandson, whom he considered worthless. "What do you want?"

"Nothing much, just cleaning up this filthy house." Shinji's expression grew colder, a stark contrast to when he comforted his sister. "I finally have a lovely sister; how could I let her be scared by disgusting bugs? In particular, a wretched old bug clung to life for 500 years. The stench of decay is nauseating just to smell."

Indeed, as Shinji said, his grandfather, or rather the one listed on the family register as his grandfather, Zouken Matou, was a five-hundred-year-old monster. Just as one would expect from someone of his age, he had completely calmed down after the initial surprise and anger.

"Where did you learn all this?" His calm tone concealed the hidden threat. He could not afford any mishaps in the meticulously planned years.

"Guess," Shinji chuckled, devoid of any amusement on his face.

Zouken's patience for conversation had been worn thin. He will capture the boy and extract the information he wants. As a great magus, it was too easy to obtain information from a person's mouth.

Contrary to the old man himself, his cane, emitting a woody fragrance, lightly tapped the ground, and the amassed swarm of insects erupted.

"Although I was mentally prepared, seeing it with my own eyes is still disgusting," Shinji's face turned pale, suppressing the discomfort in his stomach. "Sakura, close your eyes and cover your ears. It'll be over soon."

After speaking, Shinji raised his left hand and a pair of eyes suddenly appeared on his palm. The deep pupils elongated into ovals, emanating an eerie golden light similar to the eyes of the legendary winged serpent.

Anything caught by these eyes, be it a living being or an inanimate object, was coated with a layer of gray and rendered immobile.

Crawling creatures on the ground froze instantly, resembling statues. The insects in the air fell individually and shattered into stone debris.

"Petrification... Mystic Eyes!" Zouken's face changed drastically as he managed to escape behind the swarm of insects. "You... How is this possible?"

A bewitching cold light flashed, and the emaciated old man split into two.

In front of the old man, Shinji held a barely visible, long-handled scythe, announcing his death sentence:

"You deserve to die, Zouken Matou, no, Makiri Zolgen."