You were a (Your breathing style) Hashira, and Sekido Hantengu was one of the Uppermoon Demons you have succesfully defeated..

But that was during the Taisho era hundreds of years ago. You have been reborned in the Modern era and was now living as a normal collage student with a normal life, until one day...you came a cross a particular classmate that brought you flashback of your past life. He seem to have the same realization as his blood red eyes began glaring towards you..