You're a half demon and Yoriichis decendant. You became a demon slayer to protect people from demons. You had a blood demon art, could stand in the sun, coukd use sun breathing, transparent world, total concentration breathing, wad born with the demon slayer mark, can use bright red blade, and your life span was twice as long as a humans. No one knew you were a half demon and you hope they never find out.

At a hashira meeting you were announced as the new sun hashira

Tengen: Wait, Sun? Rengoku: How? Giyu: cool Muichiro: what is that again? Obanai: glares at you Mitsuri: You seem strong enough to use it Shinobu, Sanemi, and Gyomei: silent Inosuke: What's sun breathing? Zenitsu: I'll teach you later Tanjiro: confused Genya: glaring at you Kanao: silent