PK runs to the site where Marisa is at. He sees her ripping apart human after human with a bloody knife.

PK: MARISA! Don't do this! Reimu wouldn't want this you know!

Marisa stops, noticing that PK had just arrived.

Marisa: PK! You're too late! No one can stop me now!!! I am almost complete in reviving Reimu! And all I need is the blood of yours!

PK: There's no way you'll be taking my blood!

Marisa: How 'bout I do so now ze~~?

Marisa immediately lunged at PK, preparing to stab him. All of a sudden, the attack was blocked by a ghostly hand.

PK: Necros? Is that-
Necros: Unlike the other entities, I can act on my own and leave your body without any harm. You could say that I'm like a ghost that haunts people.
PK: So that means...

Marisa: DIE DIE DIE!!! *rapidly starts stabbing*

Necros: Correct. *Blocks the stabs in front of PK* I'm a spiritual stand.

Marisa: *pants* If you would die, nothing bad would happen! So why won't you DIE?!??!!?!?

PK: Because you're the one who's being psychotically insane. And I have no choice but to constrain you from killing.

Necros: Necro Sign! "Destiny Chain"!

Green ghostly chains start to form around Marisa.

Marisa: Wha- what is this?

Shackles form on Marisa, constraining her as a result.

Marisa: LET. ME. GO!!!!

Necros: I'm taking over for a sec. *possesses PK*

PK (Necros): "Night Glare"!

PK focuses on Marisa's eyes and the two are in a zone where they only exist.

PK (Necros): Listen. You have to stay strong for Reimu. She will never approve of this ever. She stay dead, and will. Even the Youkai sages or the Yama can't revive her. Just accept the truth.

Marisa: NEVER!!! YOU'RE LYING!!! I KNOW THAT REIMU WILL COME BACK!!!

PK (Necros):  If I was lying, then I wouldn't be able to communicate with Reimu herself. She knows your pain. Reimu told you to stay strong and take care of yourself.

Marisa: Communicate? YOU ARE DEFINITELY LYING!!! REIMU WANTS TO COME BACK!!! I KNOW SHE DOES!!!

PK (Necros): Then... Let's see if you're right. *removes the shackles*

PK: Hey, what are you doing???

PK (Necros): She'll understand Reimu's pain soon...

Marisa charges at PK with her knife only to be gutted by PK.

PK (Necros): As I thought... based on your actions, you have proven to be wrong. Necro Sign! "Border of the Waiting"!

Marisa is sent to another dimension.

PK (Necros): PK, I'll be right back, just gotta do some business here. *leaves PK's body*

PK: Alright. *returns to his normal state*

*******************************

Marisa: I WILL BRING REIMU BACK!!!

Necros: What are you talking about? She's right here.

Marisa:  I WILL BRING REIMU BACK!!!

Necros: What are you talking about? She's right here.

Necros lifts a finger and Reimu appears from a portal.

Marisa: *eyes widen and drops the knife as she starts to tear up* R-r-Reimu....

Reimu: Hey Marisa. Sorry for dying.

Reimu: *hugs Marisa* Yes... I'm here.... I'm sorry this had to happen to you, but it was the best way possible... I'm sorry...

Marisa hugs Reimu, all in tears.

Reimu: Now, I don't have a lot of time to reunite with you, but here's what I have to say. Stay strong, be brave, and don't revive me at all. If you do, then all the stray spirits will escape to the living. Now then, do you have anything to say before I leave?

Marisa: *crying and whispers* R-Reimu don't go...I-I don't want to lose my best friend...I-I don't....

Reimu: ...What happens in the past cannot be fixed in the present. *slowly starts to fade away* Be strong.......

Necros: ...Now then. *snaps a finger and returns back to original realm* Do you see the true reality Reimu wanted?

Marisa: *was still crying and holds her head tightly as if she completely has lost control of how she feels right now*

PK: Will she be fine?

Necros: (She'll have a lot of time to recover, yes. However, Reimu told me that there was a relative of hers that also protected the barrier.)

PK: So we are safe then... phew!

(I had to copy part of the convo to reduce time.)

I think that's the whole saga for Reimu's death. The part where Reimu is revived is canon to this story.

Go to ThatRandomTouhouGirl's third time touhou squad book to find the story where Reimu is revived. In fact, she continues this part of the story as the Deep Regression magician manipulates Marisa to revive Reimu.

Plus Speedy is somehow connected to this :\

Now I gotta update PK's Necros thing. I'll tell you one thing. He adopts a new fighting stance as a result of gaining Necros.