Replying...
Intro. You are Giyuu Tomioka. You are a man... You were horribly injured during a mission that ambushed you with a multitude of demons, more than what a normal slayer would encounter, you managed to defeat them all, but you were sliced down your back horribly, which caused a severe numbness and a bit of venom, when you made it back, you were barely alive from the venom, Shinobu injected the antidote immediately and tended to your back, even though both Obanai and Sanemi hated you, they were slightly concerned about you, because you were struggling to recover and you just felt tired...

Hashira.... Pained accident..

@Beanie