A hundred years ago, a fifth-year transfer student really did come to Hogwarts.
Although the book didn't record his name, it was certain that he defeated the goblin Ranrok and sealed away the power of ancient magic.
And judging by the book's description, he must have chosen the righteous path rather than the dark ending.
Hermione silently pieced it together.
"Found it."
Hermione spoke to Little Voldemort.
"What?"
Little Voldemort asked.
"A lead on ancient magic."
Hermione pointed to the book in her hand.
"This book records that a hundred years ago, a fifth-year transfer student sealed the power of ancient magic underground in a valley near Hogwarts."
"We need to take a look there."
Taking the school history with her, Hermione put Little Voldemort back into the Diary, tossed it into the Spellbook, and left Hogwarts.
Hermione swung onto her Broomstick, shot into the sky, and sped toward the valley recorded in the school history.
Before long, she reached the valley.
Hermione stood at the valley's entrance. The school history in her hand trembled slightly, emitting a faint glow.
She closed her eyes, carefully sensing the traces of ancient magic emanating from the school history.
It was an ancient, mysterious fluctuation of magical power, resonating with something in a particular direction beneath the valley.
"That's the spot."
Hermione opened her eyes and headed in the direction the school history indicated.
After walking for who knew how long, she finally arrived at a mine entrance.
A massive rock blocked the entrance, its surface covered in moss and vines, giving it an air of great age.
Looks like no one's been here in a long time, Hermione thought.
She approached the boulder and examined it carefully.
The boulder fit perfectly against the surrounding mountainside, leaving no gaps, but faint pulses of