ok looks like i know whos the other traitor already
from what the administrator said the other traitor didnt know that they betraying their friends, i read other manga that said something like that i cant remember the title, the person didnt know because that person have split personality.
the only most suspicious backstory is none other than shiho, why? because her story have many (i dont know how to call it) time-lapse/memory-lapse
1. when she was kidnapped, after shiba offer to play a game she cant remember anymore and she woke up she's in the hospital already, we dont know how she got that scar to her face and that big scar in her chest
2. when shiba pin her down in the house of yutori she said she cant remember what happen after that, when she woke up she's in the headquarter already, how did she get there? did shiba and yutori bring her there? dont think so
and from what the detective said she is being held hostage by tomodachi game? nah dont think so, she's really working with them, looks like she didnt know she have other personality, there so many story that didnt explain about shiho except from shibe and tenji so this two is already out of the question