I'm watching the the scene where the nurse has less than an hour until the statute of limitations and the music is trying to bring some excitement but there is no way she would admit to the crime before midnight. The whole reason she was there was to fuck around with the cops and her mistake was that in her excitement she never considered they would find evidence to link her to the second murder. If cops had somehow made the nurse confess, I would have deleted Signal straight away.
Cop in present finds out identity of killer contacts cop in past and when they finally get in contact, instead of 'Hey, the killer is so and so', we get an extended sob scene which just smothered the sense of urgency.
Like this scene where everyone knew that Tanaka Shuichi could not have committed the crimes because he was driving the freaking bus. This just feels like script where the writer wants to go to certain situations but hasn't thought things through.
SUMMARY
In terms of Japanese cop shows, its not as bad as Crisis and Ouroboros and the solving crimes in the past and present is interesting but I really can't take much more of this. Only watchable if you put it in the background while doing some housework, otherwise meh. Damn shame cause I like Kitamura Kazuki. If you want to see how thrillers should be done, watch Yami no Bansosha.