The Day Everything Changed is the first part of a three part Lucky Star Konata and Kagami story arc fanfic, and was written by Mr. Fanfic Guy. It was originally published on February 27, 2011 as a single huge chapter. Between April 14, 2012 and April 16, 2012, the author published a "Revised Edition", splitting the story into chapters like all his other fanfics, and adding some extra material.
The story starts out on Thursday June 30, 2005, the day before classes at Ryouou High School let out for summer break. Konata has had a major crush on Kagami for the last three years, but she has always been too scared to tell her best friend her true feelings. At the same time, another student by the name of Sakura Takahashi, holds a grudge against Kagami for some reason, and she feels that Kagami somehow wronged her. And the next day, Friday July 1, she makes her move.
That morning, Sakura injects a mixture of Anadrol 50 and Deiselbolan v2.0 (two of the most potent steroids in the world) into herself and later advances on Kagami with a metal pipe in one hand and a pocket knife in the other, and mercilessly and senselessly attacks the poor girl. What makes it worse is that this scene plays out exactly like a nightmare Konata had the previous night. An absolutely furious Konata then fights back against Sakura, even taking several brutal hits herself. It's an intense fight, but eventually Konata, along with Tsukasa and Miyuki, manage to win the battle, and Sakura is arrested shortly afterward.
However, despite Konata's efforts, Kagami is still injured badly enough that she has to be taken to the hospital. Once they are there, Konata finally admits to Kagami that she's in love with her. At first, Kagami doesn't know how to respond, but that night, she accepts and tells Konata that she loves her as well.
The author has created two Lighter and Softer sequels: Holiday Vacation, which details the main four characters' third year beyond the final episode of the original series through the New Year, as well as the blossoming relationships between Tsukasa and Miyuki, and Yutaka and Minami, and Lucky Star: After Story, detailing the casts' post-college lives, the marriages of the three couples, the backstories of several original characters, and the birth of Konata and Kagami's daughter. Also by the author is the Vocaloid fanfiction From Concert To Chaos (which is darker than The Day Everything Changed), and the Nichijou fanfiction Not a Normal Day, in which the Professor gets appendicitis.
This fanfic provides examples of:
- Badass Adorable / Cute Bruiser / Took a Level in Badass: Konata definitely qualifies in this fanfic, as she shows no hesitation in going up against Sakura.
- Berserk Button: Any manner of hurting Kagami riles up Konata.
- Big Bad: Sakura Takahashi.
- Big Damn Heroine: Konata when she fights back against Sakura.
- Bittersweet Ending: Leaning heavily on sweet. Kagami sustained grievous injuries and is wheelchair-bound until she heals, and Konata also sustained injuries. However, Sakura is now in prison, and Konata and Kagami are an Official Couple.
- The Bully: Sakura is a particularly nasty and realistic example.
- Cue the Rain: Right around the time Sakura moves in on Kagami, it starts to rain.
- Curb-Stomp Battle:
- Poor Kagami didn't stand a chance against Sakura.
- Also to a smaller extent, Konata versus Sakura, through the former's sheer determination.
- Dark Fic: Not nearly to the extent of something such as Lonely Kagamin or Falling Stars, but it still counts. It also helps that the weather the day of the attack really was overcast and rainy.
- Determinator: Konata when she is fighting against Sakura.
- Disproportionate Retribution: Sakura had held a grudge towards Kagami for god only knows how long. The moment she can no longer take it is when Kagami scored higher than her on the midterm. So what does Sakura do? She beats the living daylights out of Kagami, and injure the poor girl badly enough that she has to be taken to the hospital.
- Even Evil Has Standards: Sakura, while plotting, states that although she'll make Kagami suffer greatly, she will stop short of murdering her.
- However, given how she was clearly undergoing Sanity Slippage during the attack, she likely could have ended up murdering Kagami anyway if Konata had not intervened.
- Gray Rain of Depression: The clouds open up and rain starts to pour right around the time Sakura starts her assault on Kagami.
- Jerkass: Sakura, to the extreme.
- Kick the Dog: Sakura does this brutally to Kagami during Chapter 4. The most severe example is when after Kagami starts crying and begs her to stop (while Sakura is twisting her already broken arm), Sakura responds by slashing her with her knife again.
- Laser-Guided Karma: Sakura is immediately arrested after the attack, and she is sentenced to 20 years in prison.
- Not only that, but a mob of angry students tried to get at her as she was being led out of the school by the police in pursuit of vigilante justice. It took the efforts of every faculty member on the first floor to calm down the mob and safely escort Sakura out of the building.
- Laughing Mad: During Chapter 4, after Kagami tearfully begs her to stop, Sakura starts laughing in a "borderline maniacal" manner, slashes Kagami with her knife again, and finally boasts that no one can save her now.
- No-Holds-Barred Beatdown: Sakura gives a brutal one to Kagami in the climax of the fanfic.
- Oh, Crap!: At least 3 moments.
- Kagami, when she realizes that Sakura is about to attack her.
- Konata, when she figures out that her nightmare has become a reality.
- Sakura, when even after she strikes Konata several times with the pipe, she still refuses to give up fighting.
- Original Characters: Ayaka Suzuki and Nanami Tanaka are introduced in this fanfic right after the attack scene. They would later take up bigger roles in the next two fanfics.
- Prophecies Are Always Right: The climatic attack scene plays out very similarly to a nightmare Konata had experienced the night before.
- Red Eyes, Take Warning: When Konata starts fighting back against Sakura, she has what the author describes as a "bright red glow of rage" in her eyes.
- The Resenter: Sakura serves as this towards Kagami.
- Sanity Slippage: Sakura undergoes a serious case of this during her assault on Kagami.
- Secret Relationship: Konata and Kagami agree to keep their relationship under wraps for a bit, only for it to become common knowledge in the sequel. Since the sequel takes place after the main series, this creates some Fridge Brilliance, in that the Les Yay between Konata and Kagami is actually them trying very hard to cover up their relationship, and that Kagami most likely hates having to put on a Tsundere act.
- Smug Snake: Sakura, again.
- Too Dumb to Live: During her trial, Sakura makes no attempt to rationalize what she did, insisting that Kagami somehow had it coming and openly bragging that she "taught that bitch a lesson". Not surprisingly, her lack of remorse earns her a 20 year sentence.