This year's Defense Against the Dark Arts was utterly worthless. Everyone thought so.
The new professor, Dolores Umbridge, declared practical training unnecessary and forced students to endure nothing but lectures—endless reading from textbooks.
Naturally, such lessons were useless.
The true purpose of this class was to teach students how to defend themselves if attacked by dark magic.
In other words, its essence lay in practical application. Not lectures.
For example, Muggle schools have music classes. Of course there's theory involved, and students learn from books.
But there's no such thing as a music class where students never touch an instrument or sing.
That's exactly what this was like.
However, surprisingly few Slytherin students complained about these lessons.
This was because Slytherins leaned toward the dark side, with some students even having Death Eater parents.
From the dark faction's perspective, Umbridge's incompetence—preventing students from learning how to oppose them—was something to celebrate.
Perhaps because of this, Slytherin students accepted these lectures, even going so far as to curry favor with Umbridge and sabotage the other houses.
What surprised Edith was that Mirabel stayed quiet and took no action.
Given her fierce nature, Edith had expected her to fire off a dark spell or two at Umbridge with a sarcastic "Let's test whether theory alone can really protect you."
Perhaps she'd become less reckless than in years past.
Defense class was worthless, but that didn't mean the other classes were wonderful.
With OWL exams looming this year, every subject tormented students with unprecedented severity.
But there was one silver lining.
Care of Magical Creatures had a substitute teacher—Professor Grubbly-Plank—since Hagrid was absent for some reason. Her lessons were truly what Care of Magical Creatures should be: rich and fulfilling content.
Harry and his friends claimed they preferred Hagrid, but their expressions made it obvious they didn't mean it.
Also, during those lessons, Malfoy picked on Harry's group as usual—but that was nothing new. No point worrying about it now.
There were other things that deserved concern...
"'Dolores Umbridge Appointed First High Inquisitor.' Honestly, the Ministry never does anything good!"
In the Slytherin girls' dormitory, Edith read the newspaper aloud, fuming with indignation.
Most Slytherins viewed Umbridge favorably, but some students opposed her.
Edith was one of that minority.
She didn't belong to the dark faction and was quite sensible, so she felt irritated by the Ministry's methods that needlessly hindered learning.
No, that wasn't her only reason for anger.
"Harry's getting detention every single day too! Why do they just decide he's lying without even thinking? Don't they even consider the possibility that 'What if he really did come back?'"
She tore the newspaper to shreds and hurled it into the fireplace in a rage.
Watching this display, Mirabel simply giggled with amusement.
"My, my, quite upset, aren't we, Linagoul?"
"Of course I am! Ugh, why are those people so stupid?"
"Calm down. Your anger won't improve the situation."
Mirabel waved her favorite wand and conjured herbal tea in front of Edith.
Apparently she meant for Edith to drink this and settle down first.
Unusually considerate of her.
"Unfortunately, Potter and Dumbledore will continue being called liars for some time. Right now, they have shockingly few allies."
"...Can't we do anything about it?"
"We can. Once the Ministry falls to the dark faction, they'll be forced to face the truth whether they like it or not."
"That's not what I meant!"
Edith slammed the desk, making Mirabel blink in surprise before smiling with amusement again.
She sipped her herbal tea elegantly, then spoke in a leisurely voice.
"Hehe, you really do care about your friends. I can't understand why you're in Slytherin."
"Mmm..."
"Well, jokes aside, there's nothing we can do about the current situation. But not everyone doubts Potter's words."
Edith brought the herbal tea to her lips, looking dissatisfied.
Her first thought was: "This is delicious."
She'd heard that tea's flavor changes completely depending on how it's prepared, but this was entirely different from what she usually drank.
She hadn't known Mirabel understood tea ceremony.
"Granger will understand how dire the situation is and should take action soon. Then those who believe in Potter will protect him."
Harry had a talent for winning people to his side.
Even in this hopeless situation, he had friends who would forge a path forward.
He was in a difficult position right now, certainly.
But he was never alone.
"And even in Slytherin, he has one ally—you. He's fortunate."
"But someone like me can't help at all..."
"You can."
Mirabel gently patted Edith's shoulder and spoke with a soft smile.
Though her voice lacked its usual overwhelming forcefulness and persuasive power, it had a strange quality that calmed the heart.
"I told you before, didn't I? That I'd teach you how to use power to protect yourself. Use that power to protect those precious to you. Now it's your turn."
"...Me? Can I really do that?"
"You can. I know you can."
To help Harry and the others herself?
Edith had always thought such a thing impossible.
They were special, brimming with talent. Different from her.
She couldn't possibly match geniuses like Harry, Hermione, and Mirabel. She'd always believed that.
And yet she was supposed to protect Harry?
"I'll be the one teaching you. In one year, I'll make you more skilled than any professor at this school. Though it will be quite harsh... Can you keep up?"
Edith closed her eyes as if to think.
But there was nothing to think about—her answer was already decided.
...I want to become stronger. I'm tired of being left behind.
She would never forget that helplessness she felt in second year.
—Become strong, Edith Linagoul. Then you won't have to feel such regret.
Mirabel's words from back then flashed through her mind.
Since then, she'd devoted herself to studying and trained in magic.
Under Mirabel's guidance, she'd even learned the Patronus Charm.
But it still wasn't enough. She still couldn't stand beside this friend as an equal.
So...
"No matter how hard it gets, I'll follow you. So please, Mirabel! Make me stronger."
"...That's the answer I wanted to hear."
Seeing Edith's eyes filled with determination, Mirabel showed a satisfied smile.
Then, still gripping Edith's shoulder, she muttered an incantation.
A pulling sensation accompanied a complete change in scenery—they now stood in what looked like a cavern.
The sudden transition made Edith's eyes widen as she looked around frantically.
"Wh-where are we?"
"The Chamber of Secrets. Where the Basilisk once lived—a place few people at Hogwarts know about. Perfect for secret practice, don't you think?"
"N-no! How did we even get here? You can't use Disapparition inside the school!"
"Hehehe... The school's protections aren't as perfect as you think."
Mirabel's words left Edith dumbfounded.
Well, nothing made by humans could be truly perfect.
But still, this place was covered by Dumbledore's protective enchantments.
To bypass those and teleport—whatever the mechanism, it was extraordinary.
But accomplishing the impossible was exactly what Mirabel Beresford did.
Five years of friendship, and she'd just demonstrated her absurdity yet again.
"Now then, what I'll teach you... I have no intention of covering what you'd normally learn in fifth year."
"What!?"
"That would be far too slow. So I'll focus exclusively on magic for actual combat. Specifically: one offensive spell, two defensive spells, one movement spell. Plus how to cast nonverbal spells. At minimum, you need to master what I've determined essential. I'll teach you centered around that. Anything else can wait since the spells you've already learned should handle most situations outside fighting Death Eaters."
Only four spells total.
Edith looked skeptical that Mirabel called this the bare minimum.
Was that really enough? The more spells you knew, the more options and strategic flexibility you had.
Perhaps noticing that look, Mirabel smiled wryly.
"I know what you're thinking, Linagoul. A proper witch needs as many spells and cards in hand as possible... right?"
"Y-yeah."
"That's correct. The ideal witch possesses countless spells and knowledge to handle any situation."
The more spells a witch knew, the better.
That was the common understanding held by most, and it was true.
Mirabel seemed to acknowledge this, stating it was correct.
"But... I'll be blunt. You haven't reached that level yet."
"!"
"Even if you held a hundred cards, you lack the foundation to instantly select the right one for each situation. Countless cards only become a powerful weapon when backed by the processing speed and sufficient knowledge to wield them. But cards you can't use properly are nothing but a burden, no matter how many you have."
Mirabel waved her wand, producing a whiteboard from nowhere.
A marker moved on its own, drawing arrows.
More arrows branched from those, splitting endlessly.
Every branch ended with a question mark.
This diagram represented a situation where you couldn't tell which choice was correct.
"Normally, to avoid this, they build a solid foundation first. Through repeated lectures and practical training, they drill into your brain and body 'what to do when' and 'what magic to use in this situation.' Magic schools exist to teach exactly that. Following so far?"
"Y-yeah."
"After graduation, you continue gaining experience and studying, learning from mentors and real combat, understanding failure and success, solidifying the foundation to wield those cards. After years of refinement, you finally become capable of using countless spells—that's the specialist called an Auror. You're five years away from reaching that level."
How brutally honest.
Being told she was five years short—well, she could accept that.
But then what about Mirabel, who was having this conversation right now?
...Though knowing her, she'd probably dismiss it with "Because I'm a genius," which was the truly frightening part.
The more she heard this explanation, the clearer it became just how monstrous Mirabel was.
"But as I said, we don't have time. You need to close that five-year gap in less than one year and become capable of defeating Death Eaters."
"H-how?"
"Don't rush, just listen. After all this explanation, wizard duels ultimately come down to quick draw. Essentially, land your spell before your opponent and knock them unconscious—that's victory."
No matter how many spells you knew, you couldn't use them while unconscious.
That was perfectly obvious—everyone knew it.
In other words, if you achieved these two points—"landing your magic" and "rendering them unconscious"—victory was assured.
"That's precisely why the Killing Curse, which has no counter-spell and instantly kills on contact, is considered the strongest. With that, you don't need Expelliarmus or Stupefy. Naturally, that's the spell I'd want you to master, but..."
Edith shook her head vigorously.
Absolutely not, she thought.
Magic that killed your opponent on contact—even if she learned it, she'd be too terrified to use it.
Mirabel seemed to have expected that reaction and laughed with amusement.
"...Well, naturally your kindness prevents you from mastering it. Cards you can't use are just in the way... so let's discard that option. The next best thing I'll teach you is my original spell."
Mirabel pointed at a distant rock, directing Edith's gaze there.
What spell was she planning to teach here?
Also, this person casually created original spells—was she really a fifth-year student?
While thinking such things, Edith stared intently at the rock.
"What's needed for dueling magic is to hit faster than your opponent, with no dodging possible, no defense possible, and reliably rendering them unconscious. Put more simply, if you're fast enough that they can't defend or evade, that's sufficient. Therefore—"
Mirabel's fingertip flashed for an instant.
Immediately after, a golden lightning bolt pierced through the rock.
Only electrical residue remained, with the scorched rock proving an attack had occurred.
"—Voltage Erase. This is the single offensive spell I'll teach you."
Grinning at the stunned Edith, Mirabel continued.
"Living creatures called humans lose control of their body at just 0.02 amperes of current, and stop breathing at 0.05 amperes. A direct hit to the heart stops it, and 0.1 amperes is fatal."
"..."
"In other words, if you fire this faster than your opponent completes their spell, defense absolutely can't arrive in time, and evasion is impossible. And by adjusting the current, you can easily decide anything from unconsciousness to instant death. Well, even low current can kill if you're unlucky... but there's nothing to be done about that."
"W-wait a minute..."
Unable to contain herself at Mirabel's smug explanation, Edith grabbed her.
She seized her shoulders and shook her back and forth, but Mirabel's smile didn't falter.
"Wait! What are you trying to teach me? That could kill someone!"
"If you don't want to kill them, adjust the current. Easy, right?"
"You just said even low current might kill them!"
"The Stunning Spell is the same. However you adjust it, humans die when they die."
Mirabel gently removed Edith's hands and spoke persuasively.
"Besides, this isn't just for attacking. Depending on adjustment, it can restart a stopped heart. Use it properly and it can save lives too."
"...!"
"Linagoul, I'm not telling you to abandon your kindness. But if you've put your finger on the trigger in battle, never hesitate. For your own sake, and for those you want to protect."
Edith looked into Mirabel's eyes.
Those golden eyes she'd seen countless times.
But they seemed more serious than ever, as if genuinely concerned for her wellbeing.
Edith swallowed hard and replied in a hoarse voice.
"I-I understand..."
"Good answer. Now let's get right to teaching you how to use this—hurry up and draw your wand."
Thus began the secret training sessions between Mirabel and Edith alone.
Around the same time, Hermione was planning to gather students for independent study, but Edith had no way of knowing this yet.
Hermione: "There's nothing written about using Defense spells!"
Umbridge: "Well, do you really think a situation requiring Defense spells would arise in this classroom?"
Hermione: "But what about the OWL practical exam? Are we supposed to wing it?"
Umbridge: "If you study the theory, you won't be unable to cast spells."
Ron: "Let's test it."
Umbridge: "What?"
Ron: "Let's test whether theory alone can protect you."
Umbridge: "Wait, stop, what are you doing, Mr. Weasley! Stop that! Why are you dangling me out the window!? Let go, let go of me!"
Ron: "Got it." releases
Umbridge: "Huh? Ah, ahhhhhhhhh..." (echoing)
Ron: "I let go."
Harry: "( ﾟдﾟ)"
Hermione: "( ﾟдﾟ)"
Female students: "Oh my... so cool..."
Gryffindor loses 50 points.
(Author's Note) And so begins Edith's magical makeover arc. Also, the true identity of the golden beam Mirabel has used since first year is revealed. Here's an explanation of the original spell:
Voltage Erase An electric attack spell created by Mirabel. A lightning-fast strike fired with minimal motion. No special additional effects—magic purely devoted to shooting fast. Faster than a Salamander! The name's origin is probably voltage or current loosely translated and creatively interpreted.