Y/n POV
As Mrs. Shinazugawa come for me to live with them.
It happened in a blink of an eye, I saw something that going to hit me, but then Mrs. Shinazugawa was the one who got hit...no it was supposed to be me, but Mrs. Shinazugawa block it for me and then there was a Man, it was him who attack us, I was going to attack him, because he hurt Mrs.Shinazugawa, when Mrs. Shinazugawa start to act weird and suddenly attack me.
"Mom! What are you doing!" Sanemi who just happened to come and get us.
"Mrs. Shinazugawa, what's the matter" I said holding her, she was pinning me down and trying to sink her teeth to my body, I just act by instinct.
Sanemi is just stunned by what he see. I only manage to push her with all of my will when she tried to attack Sanemi.
I just protect him, I was deeply scratch in the back.
I'm already crying, what happened, this isn't
Mrs. Shinazugawa. She will never hurt anyone,
"Y/n!?" Sanemi was trembling while I was leaning to him.
I noticed that Mrs. Shinazugawa is coming back to the house where Genya is and the others.
"Move! Sanemi! That thing! Is returning to your house! Go!" I push him.
At first he protest but then he run after it. My back hurts, it was so painful.
And I remember I just faint.
3rd POV
Y/n faint from the pain,while Sanemi chase and try to stop his Mom. The kids whose waiting for there Mom's arrival and older brother were getting worried.
"Genya-niichan, it's rare for mom to go home this late"
"Don't worry Sanemi-niichan have come to fetch mom" Genya said while babysitting Shuya who is sleeping peacefully in his arm.
"I haven't tell them, she come to fetch nee-chan so she be living with us from now on" Genya thought happily.
When they heard someone opening the door. They all rush to open it.
"It must be mom!"
"Mom"
"Wait don't open it, it might not be mom!!!" Genya warn but it happen to fast.
He just feel something slash him and saw his siblings also get slash.
"An...animal...a stray mutt...no A wolf! I can't see it's dark, It's coming for me" he thought as it happened to fast.
But Sanemi charge in throwing himself along with the wolf. Genya talking about.
"Genya! Run for it!" He said before crushing down along with his used to be mom.
"Nii-chan!!!" Genya shouted.
He got himself wounded and it act drunk and he got the chance to kill it.
The feeling of killing your beloved mom with your own hands.
While Genya who saw his younger siblings bleeding, he try to help them."Sumi! Teiko! Shuya! Koto! Hiroshi! Just Press your wound hard to surpress the bleeding, just wait for me I get a doctor! " He crying said and nervous. When he go outside to look for a doctor. The sight of Sanemi bleeding and the big knife in his hand and in his foot is the bloody corpse of there Mom.
"Mom! Mom! Why?! Why did you kill mom!?" Genya who hug the Lifeless body of there Mom.
A lot on going inside Sanemi's head. He just killed his own Mother.
"Murderer! Murderer! Murderer!" Genya shout and accuse to his older brother, who just guilty and stand there, as the sun rising and not noticing there Mom crumbling into ashes.
Y/n who just woke up after being unconscious, she get up and ignore the pain in her back to see and hear Genya shouting at Sanemi who is covered of blood.
"Murderer! You murder mom!" Genya said crying and screaming.
Y/n just approach them and look to Sanemi to the there mom. She just tear up and cover her mouth and approach Sanemi.But then Sanemi just run to the mountains. He feel guilty, Guilty for killing his own Mom.
He was in so much pain. He didn't let y/n to comfort him. Y/n is hurt, even she want to chase him, she can't cause of the endearing pain in her back that is still bleeding. She was also hurt that Sanemi didn't stay.
Clearly he abandoned them.
All of the promise and what they share come flashing back inside her mind, make her more dejected.
"Come back...Sanemi" y/n last said before she faint and Genya who was still in shock. Just mourn to the remaining of her mom, not knowing why, why she turn into a ashes.
A Demon Slayer have come and saw the situation. Genya, whose still petrified from his lost of family. And the question of why his mom disappear.
Y/n who is suffering from blood loss. They only treat her and try to calm Genya.
The two were taken care by the Demon Slayer. When y/n woke up, she found herself inside a room.
"Sanemi! Genya!" She said and try to get up.
Genya who get a grip of himself come rushing to her side.
"Nee-chan!!! Don't get up yet your wound"
"Listen Genya that wasn't your Mom, Sanemi didn't kill your mom, I saw what really happened" she said while holding his shoulder and looking at him. He only slap her hand to his shoulder and glare at her.
"Why are you even!? Defending that murderer! He killed mom, we both saw that"
" That wasn't your Mom, it all happened in a flash, she was fine until something try to hit me and she got hit, and turn into that"y/n crying said.
Genya now face is full of rage and look at her. "You! If mom didn't go to convince you live with us! Mom didn't die! Shuya! Teiko! Hiroshi! Sumi! Koto! They shouldn't have died! If it wasn't! Your no different with that murderer! You killed my family! I wish we haven't met you! This shouldn't have happened! Get out! " Genya said screaming and shout to y/n whose crying and get up from the futon.
"I'm sorry... I'm really sorry, Genya... But don't blame your older brother he just tried to protect you from her... We both know that wasn't your Mom anymore the moment she killed your siblings and hurt us all" she said quietly and left.
Genya just throw a tantrum everywhere and crying. He was in despair. He doesn't know what to do.
Y/n who can walk a bit, decide to look for Sanemi.
She only go to the mountain. Where Sanemi run to, she go to the mountain still injured, she doesn't care, Sanemi need someone, he is suffering more than her. The feeling of killing your beloved one, is harder than losing them.
Her blood only lure Demons. She was in the middle of forest on top of the mountain when a demon try to eat her, Sanemi just saw her, and protect her from the demon by making himself as the bait, Good thing, Dawn is breaking and he caught the demon and just let the demon sun bath and turn into ashes. He was going to run not leaving a single word, when y/n is going to hit the ground.
"Idiot, why are you here!" He scolding said and treat her wound even he himself were bleeding.
Sanemi who is still devastated and have a suicidal wish, that's why, he is living in the mountain.
"Sanemi..." She mutter and hug him. After y/n hug him, he try to pull away and said he doesn't want her to be kill by him and he keep saying I killed my mom! I am a murderer! Let go! Don't hug the murderer! He yelling to y/n but then she didn't budge and keep hugging him.
"No need to hold back, I know it's hard, I know your hurt... Don't blame yourself... That wasn't your Mom... You didn't kill your mom... The moment she attack us, she turn into something... Sanemi... Go back...go back with me... Let us both explain to Genya..." She said quietly while hugging Sanemi who is crying and finally hug back.
Y/n just comfort him, that he fell asleep in her lap, he was tired. The heavy stuff in his chest. Have finally ease a bit and y/n just stay beside him the whole day.
The moment she woke up, she found herself inside her house.
"Sanemi!?" She said and get up but she trip. Sanemi left her, He left her.
He have left a letter to her side.
Dear y/n
As much as I love to stay and come with you, I don't deserve it, Genya probably won't forgive me about it and I don't blame him, after all I kill our own Mom, just forget about me, and live to the fullest.
-Sanemi
Y/n just hug the letter and cried.