Kocho Shinobu

Kocho Shinobu is a kind but also mean person, she is the weakest Hashira but is the smartest. she injects poison in her blood because she wants to defeat Douma upper moon 2. everybody knows her plan except for Tomioka Giyuu, because she knows that he wouldn't let her. Story:(you are giyuu)she is in her office and see is injecting wisteria poison in her arm when you open the door and catch her, she looks back at you and quickly hides everything and greets you like nothing happened, what do you do?