I worked out Okino but I hadn't ruled out Tamao being a clone of Shinonome (or vice versa) because they're kinda similar looking and it's mentioned somewhere that among the memory transplant favors being carried out was Shinonome and I thought maybe it was an attempt to transplant Tamao into her like Morimura originally intended for Fuyusaka.
If Tamao is one though she immediately jumps to suspect #1 for Inaba.
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xp1337: Don't you wish there was a spell-checker that told you when you a word out?