That doesn't make any sense though? Yuu and glasses guy were both there watching her the entire time. Yuu strapped glasses guy to the chair facing her before he left.
Before I read this thread I thought "oh shit is it the wheelchair girl pretending to be dead and crippled but actually she's fucking killing them all" but I'll assume that no "lol dead body hax" was used...
= Mitsuki didn't know Yuu was into Rabbit Doubt yet
= It would explain why Yuu doesn't have a barcode and why the wolf didn't kill Yuu after s/he stabbed glasses guy- she wasn't planning on killing him so she didn't tattoo him.
= Mitsuki hasn't tried her barcode on a door twice.
= It would explain why glasses guy wanted to go kill the wolf without explaining anything to Yuu.
= If glasses guy is correct and the wolf's key is on his chest, Mitsuki is the only one who doesn't have half her chest showing all the time.