Kimetsu no Yaiba/Demon Slayer Isekai. Female lead.

Did I Just get Isekaied?!?!

Haku sat down in the old train seat with a heavy sigh. She was heading to visit her grandparents in Japan, and travel had been extremely tiring. Jet lag was getting to her big time. The train she was on was an old style locomotive originally made in 1922 that was primarily used for sightseeing now. It would be a good time to relax and finish the last few chapters of her manga Kimetsu no Yaiba. The train she was currently on quite reminded her of the Mugen train from previous chapters. The train took off and she dug into the final chapters.

After a while she closed the book with a sniffle. "Man, I can't believe they ended it like that! My poor babies! After the Swordsmith village arc I thought Mitsuri and Muichiro were safe!" she stretched her arms and tucked a loose strand of her snow white hair behind her ear. It was longer than she usually kept it, reaching to her mid back, but busy times had prevented her from cutting it and ultimately she had grown attached to the length. She was sure her poppy red eyes had bags under them from lack of sleep. She leaned against the window intending to catch some z's when the train suddenly lurched flying violently off the tracks. Haku was thrown from her car down the hillside. She was falling.......falling......falling..... Why was she still falling? The entire world seemed to change around her. Modern Japan replaced with a Taisho era version. She hit the ground with much less force than someone ejected from a train should expect. She looked herself over. Not a scratch. The Sun and Moon haori gifted to her by her father was intact. She was however now in a hakama. The top was a pale yellow and the pants a hunter's green. Traditional tabi socks and black strapped zori sandals on her feet. In the distance was a derailed train identical to the Mugen train from her manga. "Did I just.... Get isekaied?!?! But....Truck-sama wasn't even involved? Who gets sent to another world by a train? The magic school bus maybe, but a train!" she reached out beside her to steady herself as she stood and her hand felt metal. She grasped it and found it was a black bladed katana. No, not just a katana, a nichirin sword! She looked around desperately trying to find its owner.

Not too far ahead of the clearing dusk lay the protagonist himself Tanjiro Kamado. Haku ran towards him, sword in hand. "Hey are you alright Tan- sir." she thought better of calling his name. How on earth would she explain knowing a complete stranger's name? She knelt down beside him and Tanjiro turned his head towards her, breathing shortly as he tried to focus on stopping the bleeding wound. "I'll be fine. You're not hurt are you? You must have been thrown from the train when it crashed." Haku shook her head. "No, I'm fine. Not a scratch, see." She threw out her arms and turned from side to side. Tanjiro sighed in relief. "That's good to hear. I'm Kamado Tanjiro by the way." "Namikaze Haku. You can call me Haku." she replied with a slight nod. A booming voice interrupted them. "And I'm Rengoku kyojuro. Glad to see you're safe Haku-san." Both Haku and Tanjiro jolted at his sudden appearance. Tanjiro smiled weakly. "Rengoku-san is everyone from the train alight?" The flame hashira nodded with an affirming grunt. "All 200 passengers as well as your sister and companions are safe. A few minor injuries, but everyone will be fine. You on the other hand need to focus on closing that wound. Use your total concentration breathing." He placed a finger on Tanjiro's forehead, noticing the boy struggling to staunch the bleeding. "Envision every blood vessel down to the tiniest capillary. Now close it off." Tanjiro grunted and within a moment, the bleeding stopped. Haku sighed in relief. Rengoku crouched down "Good. Mastering your breathing will come in handy. Now rest up."

Haku turned to eye the flame hashira before her. He was as attractive as well as as much of a powerful force as seen in the series. After some internal fangirling, you froze. This was......the Mugen train arc......and that meant....... As if you summoned him yourself, Upper Moon 3 Akaza appeared. Rengoku's smile faded and he turned toward the opponent before him, hand on sword. Haku looked over at the Kizuki and had to snap herself out of another fangirl moment. He was just as hot as the manga portrayed, basketball head and blueberry toes meant nothing. His eyelashes made her envious. Without much thought she grasped Tanjiro's nichirin sword and held it up in front of herself, remaining crouched by tanjiro. Akaza's eyes focused on Tanjiro. Without thinking, Haku threw herself in front of the boy just in time to take the brunt of Akaza's attack. Upon noticing Haku he lessened the force of his attack, but it still caused vibrations to run through her body. She lost her grip on the katana and it flew behind her landing some distance away. In that moment Rengoku moved to attack. "Flame breathing, second form, Rising Scorching Sun!" She felt the heat from his attack and marveled at the flames that danced in front of her. Akaza retreated, his arm split from in between the fingers up to the elbow. It healed instantly and the demon smirked, licking the remaining blood from his hand. "My my. Quick moves little girl." his eyes locked with Haku's then focused on Rengoku. "Fine sword you have there." He mused. "What is your name?" Haku gritted her teeth. She had to do something. Rengoku....was going to die.