Kimetsu no Yaiba/Demon Slayer Isekai. Female lead.

Shadow Clone Demon

Haku dodged out of the way of a demon's claws. She unsheathed her sword and slashed the head off in one swift motion. She turned and slew another, then another. This was strange. There were 20 or so demons, but all were beyond weak. A normal human could kill them. She turned in time to see Gyomei crush 5 demons at once with his ball and chain. Just like that, the onslaught was over. Genya put away his gun and scoffed. "There was hardly a fight." Rengoku came up beside Haku. "Indeed. I do not see any of those demons being the cause of the disappearances." The party walked back towards the town to find an inn for the night. Haku followed absentmindedly, lost in thought. What was up with this town? Muzan did not make his own kind so liberally. Was it a ploy? A blood demon art of some kind? She could not say for sure. She was so lost in thought she failed to hear Rengoku's warning and slipped. She came crashing down into a small pond. She splashed around a moment before getting her feet under her. Genya was reaching out towards her, obviously he had tried to stop her fall. Rengoku snorted, unable to hold back his laughter completely. Gyomei simply chanted a prayer. Haku climbed out of the water. "Go ahead and laugh! It's freezing cold in there!" She sucked in breaths like she would to use her breathing style in hopes of warming up. She felt strong arms around her and found Rengoku was wrapping his haori around her. He then lifted her up bridal style. Haku let out a small gasp. "Thanks Kyojuro, but I can walk." Rengoku kept walking. "Indeed, but my body can provide more warmth than your short strides will gain." Did he just call her short? I mean, she was not tall by any means. She only came up to the flame hashira's chest. She sighed, accepting her fate.

Haku stood mouth agape staring at her futon. The inn had only 2 rooms left. Gyomei and Genya were in one and she was sharing her room with the flame hashira himself, Rengoku Kyojuro. She was dry and warm after being carried the whole way here, including to the room they were sharing. She was in a pale purple kimono provided by the inn after she had bathed. Rengoku was in a blue pinstripe kimono. And had already slid into his futon beside hers. "What is wrong? Don't worry, I wont do anything suspicious." he mumbled something that Haku thought was 'unless you let me' but brushed it off. His reassurances were comforting, and she knew he would not lie, but she was still embarrassed. Reluctantly, she slid into her futon. Rengoku rolled over to face her, his face close to hers. "So, what troubled you so much you'd walk into a river?" Haku puffed her cheeks. "It wasn't a river, it was a pond. A puddle really." Rengoku laughed and she punched his shoulder lightly. "It was that demon we encountered. I can't help but think it was testing us to see what we were made of or to assess our numbers." Rengoku was silent for a moment. "I agree. It was strange. We should rest up in case there's more to this." Haku nestled into her blankets. She felt Rengoku pat her head and simply relaxed. She drifted off to sleep.

Gyomei and Genya left that morning, headed to a different location. Haku and Rengoku were to investigate further. Haku walked with Rengoku back towards the shrine; her face was still red. She had woken up that morning wrapped around Rengoku's arm. The hashira was just staring at her when she awoke, quite pleased at the physical intimacy.  A quick slap placed by herself to her cheeks brought her back to the present, and she shuffled ahead. Rengoku just watched amused. When they arrived at the shrine, the door was already open. Both drew their swords and edged towards the entrance. There was a rush of 20 or so demons that came flying out before they could enter. Haku slashed at them, killing several. As did Rengoku. There had to be more to this. "Kyojuro! Handle these guys and I'm gonna make a way in!" His execution of his flame breathing to take out a large number in one move was answer enough. Haku slashed her way into the shrine. Inside was a hideous sight. The demon was a misshapen mass. From its flesh spawned demons. A blood demon art that allowed it to use its flesh to make clones. Disgusting. Haku blocked as the demon came flying at her, throwing both out of the shrine and rolling them into the dense forest. Haku broke away from the demon. She looked behind her, she was near the edge of a cliff that fell into the water. She pointed her sword at the demon. "Inyo breathing, fifth form, goyo! Five slashes!" She hacked at the demon's flesh and went for the head, cutting it off. She landed gracefully and sheathed her sword. Rengoku had made it to her by then and praised her. "Good job Haku! That was a strange blood demon art." Haku blushed shyly and turned towards Rengoku who was lunging towards her, arm outstretched. Before she could grasp the situation she was falling. The demon had used what little time it had left before fully disintegrating to pull Haku off the cliff. She was engulfed in freezing water, and pain surged in her head as it slammed against the bottom. She fought to the surface, coughing and spluttering. SLAM! Her back hit against another rock and darkness took hold.