Wondercolts Forever: The Diary of Celestia and Luna

My Little Pony: Equestria Girls: Wondercolts Forever: The Diary of Celestia and Luna by Sadie Chesterfield is a "replica journal" that recounts the events of Principal Celestia's senior year and Vice Principal Luna's freshman year at Canterlot High School. It serves as an Equestria Girls companion piece to the earlier-released Journal of the Two Sisters.

Return to Canterlot High
Celestia and Luna's diary entries begin on the day after summer vacation. Celestia is in her final year at Canterlot High School before leaving for college while her younger sister Luna is in her first year as a freshman. In the first few weeks, Celestia reunites with old friends, and the typically shy Luna makes new friends and auditions for the school play.

Because of Celestia's enthusiasm for extracurricular activies and how positively she speaks of Canterlot High, her friends suggest that she run for school president.

Celestia runs for president
During school elections, Principal Potts mentions to the students that this year's elections are particularly important due to the first annual Friendship Games with Crystal Prep Academy coming up. The Games are a collaborative effort between CHS's Principal Potts and Crystal Prep's Principal Cinch to unite their schools, and Luna sees it as an opportunity to reunite with Night Sky, her best friend from middle school.

Several days later, Celestia is informed that she has been nominated for school president, and she eagerly accepts the nomination. With the help of Luna on her campaign team, she runs for president against Hurricane, the captain of the football team and one of CHS's most popular seniors. On the day of the election, Celestia gives an emotional speech, talking at length about how much she loves the school and cherishes the memories she made and her ideas for bringing the students of Canterlot High and Crystal Prep together. In the face of Hurricane's underwhelming speech, Celestia wins the election by a landslide.

After a few days of celebrating Celestia's victory, Celestia joins a meeting to discuss the upcoming Friendship Games and meets Principal Cinch, noting Cinch's rather young age in her diary entries. Celestia also reunites with her old friend from middle school, Crescent Moon, but both she and Cinch appear emotionally detached. Following this awkward meeting, Principal Potts excuses Cinch for simply having a "very intense personality".

The vandalized Wondercolt
While in the city getting fabric samples for the Friendship Games team uniforms, Luna crosses paths with Night Sky and some of her Crystal Prep friends. But when Luna waves to her, she appears to brush Luna off, lowering her spirits. Nevertheless, the preparation for the Games goes relatively smoothly, and Celestia accompanies the CHS team members to a friendly meet-and-greet with Principal Cinch.

However, when Celestia and Luna arrive to school the next morning, they discover that the Wondercolt statue in front of the school has been painted bright purple. In addition, the entire front lawn was vandalized with purple and blue streamers—the signature colors of Crystal Prep Academy. Principal Potts and school president Celestia try to mitigate the situation, but the CHS students are enraged beyond reason. While Celestia and Luna spend the afternoon cleaning the statue, Principal Potts informs Principal Cinch of what happened. But Cinch denies any involvement by her students in the incident and even suggests that one of CHS's own students committed the act in order to frame Crystal Prep.

Though Celestia tries to remain positive, she worries about the impact this incident will have on the upcoming Friendship Games and the relationship between the two schools.

A feud between schools
Student morale at Canterlot High is very low after the Wondercolt statue's defacing, and Hurricane rallies some of the students together in a campaign to retaliate against Crystal Prep. Principal Potts manages to keep the peace with her words of inspiration. Luna calls Night Sky to ask about the incident, but Night Sky doesn't know anything. She also apologizes for brushing Luna off before, saying she couldn't say hello to a CHS student in front of her Crystal Prep friends because of their competitiveness.

Some time later, Principal Potts calls an emergency assembly and informs the students that someone vandalized Crystal Prep's campus the previous night and stole their crystal Shadowbolt statue. She says if the culprit doesn't return the statue by the end of the school day, the Friendship Games will be canceled. However, no one comes forward after two whole days, and the Games are officially called off.

Celestia and Luna start asking around CHS about the Shadowbolt statue but turn up no leads. Principal Potts organizes a day for some CHS students to go to Crystal Prep and clean up their vandalized campus as a sign of goodwill. While there, Celestia makes it clear to the Crystal Prep kids that this incident was committed by only a small few and doesn't represent the spirit of Canterlot High as a whole. She also promises to Crescent Moon that she'll find the missing Shadowbolt statue for them.

Unfortunately, the situation gets even worse when the incident at Crystal Prep is made public in the local newspaper. The article only prints Crystal Prep's side of the story and misquotes Celestia. Word starts to circulate around the city about CHS's ruined image, with some parents considering not enrolling their children there. Celestia and Luna decide that the best way to salvage Canterlot High's reputation is to recover the stolen Shadowbolt statue.

The case of the missing Shadowbolt
Celestia and Luna double their efforts in finding out who stole the Shadowbolt, starting with Hurricane, who initially sparked the crusade of revenge against Crystal Prep. But Hurricane has an alibi for the night the Shadowbolt was stolen, and Luna considers the possibility of the culprit being one of their friends. Being the CHS president, Celestia is distracted from her investigation by presidential affairs, including organizing a fundraiser to buy new books for the school library. Planning this event helps Celestia cheer up a little, and she hopes for everyone to come together and move on after the cancellation of the Friendship Games.

Some time into the investigation, "Detective" Luna overhears a conversation between two girls while in the bathroom. She hears them talking about Hurricane and wanting to impress him with some sort of secret they have, but one girl silences the other before she divulges too much. Luna fails to get a good look at the girls from inside the bathroom stall, but she does get a good look at their shoes. She informs Celestia of this development, and they attempt to track the girls down.

Meanwhile, Principal Potts worries about a recent newspaper article that says enrollment applications to Crystal Prep are on the rise while applications to CHS are declining. As a result of CHS's poor reputation, the library fundraiser is met with underwhelming success and attended only by CHS students and families.

Setting a Shadowbolt trap
Celestia and Luna's investigation into the missing Shadowbolt statue finally catches a break when a young freshman comes forward with information. A few days after the Shadowbolt was stolen, the freshman was walking home through the woods and witnessed two girls hiding something in the dirt. The girls discovered him spying on them and threatened him to not say anything. However, the freshman doesn't have the best recollection of what the girls look like or the exact location of where they were digging. He apologizes for not coming forward sooner, having been intimidated into silence, but after what happened at the fundraiser, he wanted to help improve his first year at CHS.

Believing the two girls were the same ones Luna overheard in the school bathroom, Celestia, Luna, and a large group of their friends search the woods for the buried statue but are unable to find it. Instead, they decide to give the girls a reason to recover the statue themselves. Luna suggests starting a rumor at the school that the Shadowbolt statue has a priceless jewel inside it. Once the rumor has spread, they can simply wait for the girls to come back for their "treasure".

Mystery solved
After just two days, everyone at CHS is talking about the Shadowbolt jewel rumor, and during lunch, Celestia and Luna spot two girls heading into the woods near the school—wearing the same shoes as the girls Luna eavesdropped on. They follow the girls into the woods and confront them as they're digging up the statue, and they run away. Celestia and Luna give chase and soon catch them when one girl trips over and the other stops to help her.

Once they are cornered, the girls—named Milestone and Willow—reveal that they vandalized the Crystal Prep campus and stole the Shadowbolt statue in an attempt to impress Hurricane. Unfortunately, while carrying the statue away from the school, they dropped it, and it snapped into two pieces. Unable to return the statue in this condition, they buried it in the woods to cover up their crime.

At Celestia's insistence, Willow and Milestone confess what they did to Principal Potts, and though they are punished with a week's worth of detention and telling the truth to Principal Cinch, Potts is very kind and understanding toward them. After school, they deliver the broken Shadowbolt statue back to Crystal Prep, and Cinch explains that the statue was a gift from her students when she became their principal. When Celestia presents the statue to Cinch, it is revealed to be in one piece again; Celestia had worked together with a science teacher to repair it. Much to Celestia and Luna's surprise, Principal Cinch seems overjoyed to have the statue returned and restored.

The first Friendship Games
With the missing statue incident now closed, Principal Cinch agrees to holding the Friendship Games again in one week. Celestia, Luna, and their friends use this week to finish the team uniforms, reassemble their team of players, practice, and make other preparations. When two of the team's original members are forced to drop out, Luna steps in to take their place.

The following Saturday, the first Friendship Games between Canterlot High and Crystal Prep are held. The Wondercolts win the first event, the Shadowbolts win the second event, and the final event results in a tie. As everyone figures out how to decide the winner, Celestia gives the trophy to the Shadowbolts as a sign of their newly forged friendship, and the Shadowbolts graciously accept.

Some time later, news of CHS's generosity reaches the newspaper stands, and the school's reputation is restored. In addition, two Crystal Prep boys are so moved by Canterlot High's gesture that they come forward and confess to vandalizing the Wondercolt statue. In lieu of punishment, Principal Potts tasks the boys with helping to clean the Friendship Games stadium. When asked about next year's Games, Potts decides to hold the Games every four years instead to make the occasion special.

Celestia's closing words
In the diary's final pages, Celestia writes that she is graduating in a few short weeks and writing her graduation speech. As opposed to saying goodbye to everyone and the school she loves, she plans to say "see you soon" instead. Finally, she expresses hope of coming back to Canterlot High School someday – maybe even as a principal.