Demon Slayer: The Obsessive Thunder Pillar

In her previous life, Wang Jiale was an orphaned swordswoman. In this life, Chiyo Le transmigrates into the world of Demon Slayer wearing two masks: obsession and tenderness.

At ten, she was saved by the former Flame Hashira. At eleven, she met the young Kyojuro Rengoku, and from then on, that flame-like figure became her sole obsession: she had to survive, and she had to make sure he belonged to her alone.

To break the curse that doomed those bearing the Demon Slayer Mark to die at twenty-five, she traded her own blood with Tamayo. To protect the person she loved, she wagered her life in every deadly battle. In the fight against the Upper Ranks, she and Kyojuro stood back to back and cut down Akaza. Inside the Infinity Castle, she used a bronze mirror to shatter Kokushibo's pride. In the final battle, she exhausted her regenerative blood to save every Hashira.

Everyone survives. No one falls.

When sunlight dispelled a thousand years of darkness and the Demon Slayer Corps was officially disbanded, the obsessive girl who once thought she was unworthy of love finally wore a white bridal kimono and married her sun.

“Kyojuro can only be mine.”

No breaking up the canon couples; there is a pairing, and it's with Kyojuro. Everyone survives.