𝐋𝐚𝐮𝐠𝐡𝐭𝐞𝐫 𝐨𝐟 𝕯𝖊𝖆𝖙𝖍 [JJK x Black Butler]

ʙᴏᴏᴋ ᴏғ ᴍᴇᴍᴏʀɪᴇs 1

Author Note:-
I don't know about the Undertaker's past, so mostly will be made up. Another thing is that I read some theories about his past as a human, so I will use them. You can find them in Google if you're interested. Also, here's another thing, I'm switching Ciel's grandparents' genders. The rest will remain the same.

Claudia Phantomhive = Claude Phantomhive (Ganderband).
S/N = Son Name.
H/N = Husband Name.

Hope you enjoy.
RC~😋

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❝My past is just faded memories, I never bothered to recall them.❞
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It has been weeks since Y/N was gone. Yuji was really worried that she suddenly disappeared without any trances. He visited her shop several times, but only to find it closed. He couldn't understand where she went and hoped that she was alright. That day he was excited to tell her about the baseball game and how he and Nobara exorcised a special-grade curse, but he returned with disappointment after several attempts to visit you surprisingly.

Today was no different at all...

It was a day off for everyone in the school and Yuji decided to visit today as well. However, he was stopped by Nobara and Megumi, "Where are you going?" Nobara asked with her hands on her hips while raising an eyebrow suspiciously. Yuji sweatdropped, "As usual, going to see if Y/N san has returned." He laughed nervously as he scratched his head.

"I'm going."

"Me too."

Both of Yuji's friends uttered which surprise him, "O-Okay... I guess." He said, mumbling the last part to himself.

"We are coming as well!"

The three students turned around only to see their sensei along with Nanami. "Huh? Nanami san, what are you doing here?" Yuji asked which earned him a sigh from the adult, "I believe I'm in debt with Y/N san. I never show my gratitude for saving my life back then. I came here to guide me to her shop again." He monotonously said, fixing his glasses. Yuji nodded in understanding and started to lead the way to Y/N's shop.

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"It's still closed..."

Yuji trailed off, sighing afterwards with a look of sadness painted on his bright face. Gojo hummed and approached the door, "How long has it been closed?" He asked, his eyes never leaving the door. Yuji thought for a moment before opening his mouth, "I think four weeks now." He said, not sure of his answer. The albino man put his hand on the knob and twisted it, only for the door to open. Yuji's brown eyes widen, "H-How?! I tried it and it's locked everytime I try!" Yuji exclaimed and the rest looked at him with a disappointed looks.

They all got in and started to look around for any leads to Y/N's whereabouts, but nothing was found. They searched in her office, room, lab, and basement, but to no avail. Yuji even went to the secret room where Junpei was, but the boy was also gone. Did Y/N really left him again? When Yuji was about to leave, his eyes landed on a book on top of the desk. He picked it up and read the title, "Fading Memories? Is that Y/N san's journal?" Without wasting anytime, he rushed to his friends, "Guys! I found her journal! Maybe she wrote something about leaving." Yuji exclaimed, being proud of his new achievement.

Nobara however hit the back of his head, "Idiot! Don't you ever read a woman's private diary!" She scolded with a scoffed. "It will be alright, we just want to know where Y/N san went." Gojo spoke up, grabbing Yuji by his side. Nanami crossed his arms as his brows frowned, "It's her privacy, we can go further then that." At his statement, everyone went quiet.

They didn't know what to do. Should they just leave like nothing happened? Or should they check the journal if she wrote something recently? They couldn't decide which one to pick. They have already stepped over the limits and entered her shop without permission let alone reading her diary. This was too much...

Megumi took a deep breath and spoke up, "As much as I hate to read her journal, we have to do that. Y/N san might left the shop and left this book behind on purpose." He explained which somehow convinced the others. Gojo put his hands on Yuji's shoulders and smiled, "What are you waiting for? open it." Yuji hesitantly nodded and started to open the book, he read the first lines in the first page...

"Whomever open this book, shall witness my memories... Memories of happiness and pain... Memories I don't want to live again..."

Just as Yuji finished reading, the book started to shine bright white and Cinematic Records started to shot out. "What's happening?!" Nobara asked with a panicked tone. The salmon haired boy couldn't answer since he doesn't know what happened... The light got stronger until it blinded them all...

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Yuji's POV:-
I slowly opened my eyes, feeling a bit weird. I didn't know what happened, I just kept on staring at beautiful chandelier...

WAIT!!!!?

Chandelier?! I swear Y/N san did have one in the shop. I quickly stood up and looked around only to find us in a fancy castle, but it's wasn't the shop... this place is different and... pretty old. I looked around me and found sensei, Nanami san, Kugisaki, and Fushiguro still passed out. I freaked out as I stood, "Wake up all of you!!!" I screamed which made them wake up. Fushiguro rubbed his head while looking at me, "Can't you be any louder?" He said, slowly standing up.

"Where are we?" Gojo sensei asked while observing the area around us. Nanami who was also looking around carefully spoke up, "It seems we are in an old era or something from the appearance of the place." He stated. I don't get it?!

"You really made sense, human."

All of the heads turned to the new sarcastic voice, "SUKUNA!!" I exclaimed as I saw Sukuna standing there. Wasn't he in my head!!!? We all took our fighting stances, ready if he tried anything. However, he just tsk-ed and crossed his arms, "I'm not in the mood to fight, I actually want to see Y/N's memories." I gave a puzzled looking which made him sigh, "You're in her memories, you brat!" He yelled at me. Before I could say anything, a small voice yelled...

"MOTHER!? MOTHER?!"

We all turned and saw a little boy running toward us. He completely went through Fushiguro like he was air, "It seems we will only observe, that's good!" Sensei exclaimed and we all turned to watch.

Third Person's POV:-
As they watched the kid, a woman with long H/C hair came out of one the many rooms with a gentle smile on her face, "Ah S/N, how was your day with your father?" The woman softly said, hugging the little boy.

Upon closer inspection, the four males and female gasped while Sukuna went slightly wide eyed...

"Y/N SAN!!!!?"

Yup, this woman is our dear Y/N san...