Demon Slayer: I'm Upper Rank One's Little Sister, So What?

(Couple pairing: Tokito. If you don’t like it, please don’t read.)

Tsugikuni Seiyu, the Kamado family’s adopted daughter, hadn’t spoken since she became conscious. She had forgotten many things, but seemed to remember having two older brothers. When she was twelve, a woman named Amane came to visit and told her that the Demon Slayer Corps held the answers she was looking for.

So she left the Kamado family and joined the Demon Slayer Corps. At fourteen, Tsugikuni Seiyu became the Pillar of Words in just one month. It was a Breathing Style she had created herself, using words to bind her enemies and her blade to cut down evil.

She could speak, but every word came at a cost.

That same year, Tsugikuni Seiyu met a cold-faced boy who had also lost his memories.

His name was Tokito Muichiro, and he was adorable.

Later, a Pillar meeting was held, and Tanjiro and Nezuko appeared before the Demon Slayer Corps. Tsugikuni Seiyu learned the story of her second brother, Yoriichi, and the terrible news about the Kamado family.

Tsugikuni Seiyu remained calm. She went to find the real culprit and fought him. There was a fire burning in her heart. No matter how much she smiled on the outside, she was still... furious.

The final battle at Infinity Castle.

As the sound of the biwa rang out, Tsugikuni Seiyu gripped her Nichirin Blade and finally came face-to-face with her long-lost elder brother.

Upper Rank One, Kokushibo.

“You really are infuriating, Brother.”

(And Kokushibo, you’re going to work a summer job for me too!)