Before she arrived, Yang Xiao and the team had established a new code, so she could confirm the guy hiding in carriage No. 3 wasn't one of their own.
Without hesitation, Takagi Reina immediately returned to carriage No. 1, signaling Kato Shinjiro about Yandeta Chiyoda's hiding place through gestures.
After confirming the understanding, she returned to carriage No. 2, found Sakai Misaki, and first communicated the code, informing her of Kato Shinjiro's location with precise details, before handing over the ticket and Half Ghost to her.
Since each person can only be selected once per night on the electric train, Takagi Reina wasn't worried about Sakai Misaki turning on her and returning the ticket and Ghost; it was impossible.
After getting rid of Half Ghost, Takagi Reina was nearly completely safe that night, unless she actively provoked the ghost passengers.
She wasn't that reckless yet.
