It was a nice day in Gensokyo until Reimu blasted off the roof of Himari's house without warning!

Vạn Thư: WHAT THE HECK!?

Vạn Thư shouted in an angry face when Reimu suddenly hovered above her in the very early of the morning. Vạn Thư was having a very nice and comfy sleep without any major incidents until Reimu personally ruined her sleep for no good reason!

Reimu: I could smell the Yokai stench from your body as far from my Shrine!

Flashback

When Reimu destroyed the Fountain of Miracle in the previous event Yukari was quick enough to recollect the remaining water from the Fountain through her portal then stored it inside a bottle. As she wanted to experiment its power she decided to pick the worst kind of person for it: Vạn Thư. During her sleep Yukari poured a few drops of bottle into her open mouth to experiment her theory. She instantly sensed the Yokai aura emitted from her after its effect.

End of flashback

Vạn Thư: Explain your reason for ruining my sleep now!

Reimu: Your body is full of Yokai energy you know?

Vạn Thư suddenly realized something was wrong with her body.

Vạn Thư: Don't tell me…

Reimu suddenly flied toward her without any warning! Vạn Thư dodged and flied away

Vạn Thư: Since when I got this power!? Not even a normal librarian could fly!

Reimu: You had the exact Yokai scene of Keihatsu back then. That's means you had been exposed to the Fountain last night!

Vạn Thư: Nonsense! I don't even leave my house at night! What makes you think…

Suddenly she realized something wrong

Vạn Thư: It was Yukari wasn't it!?

But there was no answer from Yukari nor any sign of her appearing from the portal

Reimu: Yeah it was her though. Still, I will keep an eye on you from now on.

Vạn Thư: Hold on! I don't even have any ill intention toward you! Why did you have to be hostile against me?

Reimu: Because I'm a Yokai exterminator. Even a normal human like Kosuzu would become a part of my blacklist if she got corrupted into a Yokai by her youma book.

Yukari meanwhile enjoyed the scene with a smug while hiding behind her boundary. She also had that bottle on her desk. Ran asked her with curiosity.

Ran: Why did you test it on her instead of other, Miss Yukari?

Yukari: Because she is a best target for doing it. She always said she wanted to retire but in reality she secretly wished for the opposite. Eventually I'm doing her a favor by giving her what she wished for. She might burn the scroll about the Fountain of Miracle but her mind would never forget about such power after she witnessed Keihatsu demonstration of power.

Still, because I only give her a few drops so she won't become insane like Keihatsu while her power would be constrained within a few days at best.

Ran: You did test on yourself right?

Yukari: Nothing happened on me so far. It seem like it only worked on a librarian or a normal human. Still, I won't waste it on the other target especially the other Yukari.

Ran: Huh?

Yukari: Alternative Yukari would be the one who wanted it the most because she feared she couldn't fight against me or opposing my reign upon Kotou. This was why this bottle must be kept in my boundary faraway from her reach. So far I will keep experimenting on this 'retired librarian' to see how it actually worked.

Eventually what Vạn Thư feared finally became true. Marisa requested for a Danmaku battle right after she heard about the suddenly surge of power inside Vạn Thư body.

She knew she couldn't decline because Mamizou already gathered the other Yokai to watch the fight and place their bet. If she rejected Marisa's offer Aya would release her newspaper and her reputation inside the Human Village would be ruined as none of them could live with a Yokai like her.

Essentially she had to make a Danmaku battle at the Hakurei Shrine so that she could shut Aya up.

Marisa: I always knew one day you would face me with full power!

Vạn Thư: Who told you about that?

Marisa: It's just my instinct though. After all I'm an equal Yokai exterminator just like Reimu too!

Marisa showed her confident smile while Vạn Thư looked at her with a tired face

Vạn Thư: In the end my plan for retirement failed…

Yet what she experienced so far was beyond her imagination. Not only her power exceeds the normal power of a librarian but she never feels constrained by her own power. She never lost any of her magical power every time she used her spell.

It only took her a few seconds to cast the spell from her scrolls instead of taking half an hour to cast a spell. She could also summon any scrolls out of thin air with just a simple thought by searching her memory for any scrolls she used to possess. And more importantly, her ability to fly was the thing that no librarians had with the exception for Keihatsu.

Vạn Thư: (No wonder why it was so alluring for both of us, it completely removed all of the weakness of a normal librarian and enhanced it to the level of a God. This is a God power!)

The Danmaku fight happened as Vạn Thư realized she could fight on pair against Marisa just like how Keihatsu used to fight on an equal footing against Reimu. Eventually both of them collapsed unconscious as the fight just keep dragging on without an end.

Reimu was quite amazed about such power. Yukari who sat next to her explained what happened. Reimu looked at her with an annoyed look.

Reimu: You are the worst kind of Yokai I ever met, old hag.

Yukari: Vạn Thư had been in a crisis where she couldn't know whether she should retire or return. I simply helped her choose the right choice.

Reimu: Her choice or your choice?

Reimu looked at her with a suspicious look, Yukari simply smiled in a very 'innocence' way

Yukari: Still, you should take care of her from now on. The magical water only lasted for a few days.

Reimu: HEY! GET BACK HERE AND TAKE RESPONSIBILITY!

Reimu shouted in anger but Yukari disappeared into the portal before she could catch her!

Meanwhile at the tree house of the Three Fairies of Light, Cirno had to stop the flame from spreading further by using her ice magic as Vạn Thư's spell hit the wrong target and burned the whole place at the outskirt of the Hakurei Shrine! The fairies had to splash the water to their house out of panic.

Luna Child: Our tree house is on fire!

Sunny Milk: Who burned our home for no proper reason!?

Star Sapphire: It was the Danmaku fight earlier between Marisa and Vạn Thư!

Sunny Milk: So this is a declaration of war against us! We will pull out the worst prank of the century for provoking us!

The three fairies looked at the Hakurei Shrine with a burning desire to inflict misfortune against those who provoked them!