They would get stuck in a different realm, it was the exact copy of the human realm, but no Wistera, no people, no daylight, the realm had a blood red sky, black moon, and thousands of demons that had been slain roamed around that realm. It started only with y/n being stuck in the realm for 6 hours before her soul would return to the human realm. Y/N didn’t tell anyone about it because she didn’t want to spread it or have someone thinking she was mentally ill. She would have to survive the 6 hours, without protection. So when she was in the human realm she would watch other train and use the knowledge of what she saw in the phantom world so that she could survive. If she got hurt in the phantom realm, the injury would show in the human realm, but her pain would still be there and scars would show. If y/n changed her appearance, like cut her hair, or changed clothes, her shadow in the human realm would reflect that, not what she looked like in the human realm. But she could never die in the Phantom realm, only get hurt and bleed ‘til she took care of the wound, but never would be able to die until she died in the human realm. Until the Hashiras and Ubuyashiki family ended up finding out about it, they had found out about the phantom realm through a remaining dying demon simply saying “whoever you have in our realm knows what they’re doing.” And soon the Hashiras and Ubuyashiki family started going to the Phantom realm. They found y/n and Genya running to a scrapyard. Y/N’s head was bleeding, Genya’s side had been scratched, but they moved as if they weren’t hurt. They both had many scars from the phantom realm. The Hashiras had won the final battle, Muzan and demons were dead, there was some stragglers, but demons had come to an end in the human realm. Kagaya didn’t have the curse anymore and he was able to see. All the Hashiras were alive. Kagaya couldn’t believe that his daughter was being altered through a phantom realm and human realm while everyone else slept. Gyomei couldn’t believe that y/n’s gentle and young (14) soul would have to go through that. Sanemi and Obanai understood why y/n asked so many questions about fighting. Shinobu understood why y/n asked questions about medical conditions and treatments. Mitsuri, Tengen, and Rengoku understood the importance of what y/n had been hiding and why. Kanata, Kuina, Kiriya, Hinaki, and Nickika all didn’t like that their younger sister had to go through this.