Not sure if anyone else mentioned this before, but;
I think Rum is between Wakasa Rumi and Wakita Kanenori.
My guess is Wakasa Rumi was probably Rum, until the death of Kohji Haneda. It affected her and she did something that led to her being exiled/'killed off' by the BO.
At that time, she was also most likely Asaka, that bodyguard who went missing 17 years back. This possibility fits her age, her combat capabilities (like how she KO-ed the 3 thieves in the school shed in a single strike each, not making it look too brutal), and the 'image' of her in the past in that suit.
The scars on her arms and her sadism may or may not have played a part in her being Rum before.
Well, to be honest, the main reason I think she's the previous Rum is because of her current name.
Wakasa Rumi > I was AKA Rum
Though, I don't know if the BO does this kind of member replacement.
But this possibility could also explain why there's tension between Hyoue Kuroda and her, how he was possibly on her trail when she was still Rum.
One minor reason, she was seen to be smarter/sharper than Kudo in that Skeleton Case, providing him with hints more than once, fitting for a #2 in the BO.
Now for Wakita Kanenori. Basically, since I feel that Hyoue Kuroda is a real officer, and that Wakasa Rumi is who I think she is, Wakita Kanenori the bunny chef should be Rum, unless *plot twist* it's someone else other than these 3 suspects.
There is also this theory on his name, where Bourbon received a text from Rum with the phrase "Time is money".
Time is money > Tokiwa Kanenari > wakiTa Kanenori
But I'm probably wrong. Haha.
