Disclaimer: Neither the characters nor the basic story are mine. This is a parody of The Tale of the Three Brothers. For the original, please refer to the final volume of the Harry Potter series, or just Google it.
Enjoy.
The Tale of the Three Sisters
One day long ago, three sisters decided to go out travelling Gensokyo together. At twilight they came to a treacherous river that had taken the lives of many people who had attempted to cross to the other side. The sisters, being danmaku specialists, casually flew over the river. No sooner had they set foot on the opposite bank when they saw a ribbon-covered figure blocking their path forward. This figure was none other than the river youkai herself, and she was outraged that she'd been cheated out of three new victims, since most humans usually drowned in the river. However, she was cunning and pretended to congratulate the three sisters for being able to "evade" her, offering each of them a prize for their skill.
Yuka, the eldest and most boastful of the sisters, desired power over others, and so she asked the youkai for a device that would allow her to blast through any spellcard with a single Spark. So the youkai walked to the river bank, picked up a parasol, built a spell for a giant laser into it, and gave it to Yuka, promising her that the enchantment in the parasol would be the most powerful weapon in creation.
Eirin, the middle sister, was an arrogant woman and wanted to humiliate the youkai even further, so she asked her for the power to bring people back from the dead. So the youkai walked to the river bank, picked up a hat that somebody had left there, and gave it to Eirin, promising her that when she wore it, the hat would give her the medicine to bring back the dead as she had requested.
Yukari, the youngest and wisest of the three sisters, was a humble woman and did not trust the youkai at all. Rather than ask for something to further her own desires, she asked for something that would enable her to leave the river and not be followed. The youkai, knowing she may have been outsmarted by Yukari but not wishing to betray her true intentions in giving the sisters their "gifts," offered her own gap-making ability that she used to sneak up on people with and taught it to Yukari with very bad grace. This was no ordinary ability, as it provided everlasting protection to its user and gave a hiding place that would not be found over time, as most hiding places often are. With this, the youkai stepped aside and allowed the three sisters to continue on their travels as they admired the youkai's gifts and talked of their adventure.
Eventually, the three sisters separated, each heading toward her home. Yuka reached a village and sought out a witch with whom she had a quarrel, engaging her in a duel that left the rival witch dead on the floor. Yuka then proceeded to a nearby inn, where she celebrated her victory and drank heavily in the process. She then drunkenly boasted of her unbeatable Spark she had snatched from the river youkai herself, claiming it made her invincible. Later that night, an ordinary witch who had overheard Yuka's ravings crept up to Yuka's room. Finding Yuka unconscious and sake-sodden, the witch took the parasol from Yuka's belongings and, for good measure, moved the enchantment into her mini-hakkero and Sparked Yuka in the face, winning mastership of the Master Spark for herself. While Yuka was not killed, her fury turned her into a youkai. So the river youkai took back her first victim and made her one of her own.
Meanwhile, Eirin returned to her own home on the moon and took out the hat. As the river youkai had instructed her, she placed the hat securely on her head and, to her joy and astonishment, all the knowledge of every medicine appeared in her mind. However, she was tempted into creating the Hourai Elixir with the help of the Princess she had raised. They drank it and became immortal, and they suffered due to the fact that they were no longer accepted in the Lunar Capital that she herself had helped create and were exiled to the Earth. Upset that the hat could not tell her how to remove her own immortality, Eirin thought that she could no longer be considered "living". So the river youkai took back her second victim, its influence even reaching the Moon.
Though the youkai searched for many long years, she was unable to find Yukari, who successfully hid from the youkai for a good many years using the power of gaps. Finally, when she was a ripe old age and had lived a long and happy life forgotten by the mortal world, Yukari decided to step out of the home that nobody could find as a youkai of boundaries. Yukari then greeted the river youkai as an old friend, and together they lived in Gensokyo as equals.