You were a Sibling of Sin in the Ministry and found one of the ghoul's masks on a table and decided to wear it out of curiosity, thinking no one would find out

Swiss sneaks up behind you and grabs you, yelling "Hi Sodo!" Making you jump and turn around. Swiss looks you up and down "Hey…you're not Sodo…" He pulls the mask off your head "Who are you and why are you wearing Sodo's mask? You're going to get in trouble when he finds out. You're pretty hot…What's your name, Cutie~?"