Tanjiro's POV:
No!!! Serena was taken by some demon! I'm not going to let her die! The first time, I met her... this was love at first sight. I fell in love with her. Don't worry, Serena! I'm going to save to you! If I have to sacrifice my life for you!

Zenitsu's POV:
Serena-chan was taken by a monster!!! No way! I'm not letting anyone take away my future wife! Even, I don't want to die alone too! I just want to make a happy family!

Inosuke's POV:
What the hell?!! She got taken away by something?!! I am so going to get a demon, who's responsible of this! I'm going to rip them apart with my nichirin swords!

Serena's POV:
I was still struggling to get free from those threads so I quickly pulled out my nichirin sword and, I got rid of the threads until I fell onto the ground so hard.

"Ouch! Ouch! Ouch!!! Why do I end up getting hurt?!! I really hate this!!!" I said to myself as I stand up from the ground until I realise, I got lost. Even, I'm far away from the others too!

"Tanjiro! Zenitsu! Inosuke! Where are you?!! I'm lost!!!" I said as I begin to cry in fear.

"If one of my friends were here... they will just call me a crybaby for crying about something..." I said to myself as I lean against the tree. I looked around of my surroundings as I saw spiderwebs everywhere. This reminds me of one of the evil monsters, who I fight to protect the people.

"Maybe I should sing to myself so, I can calm down... Even, pretending nothing bad will happen too..." I said as I was trying to cheer myself up so I begin to sing.

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When I finish singing until I feel something on my arms, legs & my waist too. When I looked, it was the threads again. Even, the threads got super tight on me until I was lifted off the ground. I screamed & cry so loud in fear. I didn't realise, I still have my sailor moon powers.

[There should be a GIF or video here. Update the app now to see it.]

As I was still screaming & crying in fear until I heard someone in front of me. When I look at the person, I was shocked to see, it was a boy in front of me.

"Who are you..? You're not a demon slayer but, you have a nichirin sword with you" he said as I was shaking in fear because I realised, he's the one, who's using the threads.

"I-I-I'm S-Serena... y-you are..?" I asked him as I was trying to not make him angry. "My name is Rui. So, tell me... Why did you come with the demon slayers to Mt. Natagumo? You do know, you're not going to live" Rui said as I was trying to ignore, what he said but I answered him.

"T-The crow told them to come here! Also, the old woman told me to go with them for some reason too! I don't wanna die!" I said in fear as I was really scared of heights until I saw Rui making something out of the webs in his hands.

"Here's a new question for you, Serena. What was that song you were singing... Do you sing it to someone special?" Rui asked as he was curious. "I... used to sing to my little brother..." I said as Rui was caught off guard by my answer.

"You... have a little brother...?" Rui asked as he was looking at me. "Yes... I sing a song to my little brother, whenever he has a nightmare... I sing him a song... No matter what happens if, he's not my real brother. I will always love him as my real little brother..." I said as I smiled at my happy memories of my little brother even, my parents too.

"This feeling... you said, 'no matter what happens if, he's not your real brother... you always love him as your real brother. You will always love him'. This is the feeling, I was looking for all this years...
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You are the perfect elder sister to the role for me"