Unlimited Magical Academy, or Magicademy for short, was a relatively standard Love Simulation Game.
The Protagonist comes from humble beginnings, and due to the extraordinary magical power she holds, she is allowed to enter the school with a full scholarship.
She then meets her Potential Suitor, and as she improves her skills, works through minigames, and chooses a path through dialogue scenarios, she eventually establishes an intimate relationship and cultivates love with a Potential Suitor. The goal of the game is to achieve a romantic, happy ending.
Incidentally, there is no "harem ending", and the Route that the Protagonist ends up going down is strictly determined by choices the player makes.
In every possible Route, the role of the rival character is played by the same villainess – Cain's little sister, Diana Elgrandark.
To contrast against the humble, naive, and gentle personality of the Protagonist, Diana was designed as a haughty young duchess with a prideful, stubborn, and prejudiced personality.
As far as appearances go, to contrast against the Protagonist's pink, bobbed hairstyle, big droopy puppy eyes, and small stature with a softly curvy silhouette, Diana had long, curly blonde hair, a pointed chin, almond-shaped eyes, and a bombshell body that was big in all the right places, while still being slender.
When Cain looked down at his feet, his two-year-old little sister was rolling around on the floor.
Her arms and legs were still stubby and squishy.
This little one, so cute and round, is going to grow up into that bombshell beauty? Seriously?
It should be mentioned that in these Love Simulation Games that are generally designed for girls and young women (also known as Otome Games), the "Potential Suitor" characters usually have dark pasts and moody personalities. They are usually closed off and have troubles that they can't easily talk about with other people.
The Protagonist then comes in to his life and helps solve his inner conflicts. This leads them to form intimate bonds and makes the Protagonist the one and only person that can truly understand the Potential Suitor.
In Cain's case, his inner conflicts were meant to be "being on bad terms with his younger sister", "not receiving enough love from his parents", and "dealing with the pressure of being the heir to the Duchy".
His problems all stemmed from being the eldest son of the Duchy, being subjected to a strict education while his younger sister was spoiled and received all of his parents' love, and as a result, feeling jealous of his sister, who simply acted like that was the natural way of things.
Cain already had the memories and experiences of a man in his thirties, so while his duke and duchess parents were raising him, he could see that they weren't being especially oppressive towards him or biased in favor of his sister.[Read this novel and other amazing translated novels from the original source at the "Novel Multiverse dot com" website @ novelmultiverse.com]
He was in the body of a five-year-old child, but on the inside, he was a salaryman in his thirties. He couldn't possibly start sulking, saying, "My little sister stole my mommy's love from me!" Rather, he was busy adoring Diana, just as his parents were.
It had actually gotten to the point of their mother getting a little jealous of Cain, saying, "Diana's spending all her time with you, Cain! Let your mother dote on her, sometimes, too!"
Since he had already played all possible Routes of the game and edited the video in which he was going to present his thoughts on the storylines, he knew that "Unlimited Magical Academy" itself was the real tyrant, at Diana's expense.
The game went out of its way to twist the plot in every conceivable way just to get to the point where the player could say "That's what you get, loser!" to Diana, and even as Cain was playing the game, he found himself laughing and saying out loud, "Are they seriously gonna do her like that?"
The player, naturally, controlled the Protagonist in the game. During the first and second Routes he played through, he was saying things like "That's what you get, Diana, ya loser, hahaha!" and "This is for getting in the way of my quest for love!" in his falsetto voice, for comedic effect.
On his fourth Route and fifth playthrough, though, he was saying things like, "All right, all right… that's a little overkill, don'tcha think?", "Nah, I want a fourth option that's not even on here!", "Do we really have to do her like that?!". His sympathies had shifted completely from the Protagonist to poor Diana.
When he glanced down, he saw his adorable little sister working hard at tying his shoelaces.
It didn't seem right that his innocent, adorable Diana would be banished, or abandoned in a forest full of demons, or married off to some old geezer forty years her senior, or even sentenced to death.
For now, he had been given the role of Cain Elgrandark, a Potential Suitor, and since he had within him a salaryman in his thirties, he could ensure that Diana would not meet an unhappy ending by steering the story down the "Cain Route" – a Route of his own creation. He considered this plan to seduce the Protagonist and bring about the Cain Route into fruition a last resort.
It was possible that if he helped raise Diana to be a kind and good-hearted girl, she wouldn't even become a villainess in the first place. Even if there were some compelling forces hardwired into this world, as long as he watched over her as the eldest son of the Duchy, he should be able to command people of lower rank and manage to keep her safe.
Cain thought to himself – Ah, there's a crown prince among the Potential Suitors, though. Even as an heir to a duchy, I don't think I'd be able to oppose royalty.
In the Crown Prince Route, Diana becomes the Crown Prince's fiancée before school even starts.
Then, at the graduation party, a cancellation of their marriage is avoided in a twist, and after they go through with getting married on paper, Diana is sent off to marry an aristocrat in a far off land. She becomes a second wife to an old man forty years her senior and is forced to take care of him while being constantly insulted by her stepchildren.
Playing through it, you could practically see the game creation staff saying "Didn't expect that, did ya?" with proud smirks on their faces. How irritating.
Cain was going to protect Diana – that much was clear.
It was true that in the game, Diana was always getting in the way of the Protagonist's quest for love, and she was prideful and annoying.
However, the Diana that was currently chewing on Cain's shoelaces and getting them all wet didn't have a speck of wickedness in her.
Above all, in this life, she was Cain's little sister. His flesh and blood. She was family to him.
There was still a long span of sixteen more years until the end of the game. He still had plenty of time to make things right.
No matter what, he would defend her.
Cain swore to it, then and there. She was this adorable, after all.
With shoelaces in her mouth, she looked up at him.
"Bwoth- blegh!"
She had been chewing on more shoelaces than she had bargained for. Diana threw up, all over Cain's shoes.