Yanno when I first watched the Japanese adaptation of Signal, I really can't help noticing that there was at least one case that were in the original that weren't included in the Japanese version. I usually assume that it's because Jdrama tend to have shorter runs so when adapting from Kdramas that had twice the usual length, some parts from the original would have to be omitted.

To be fair, I never expected the series to revisit the case--heck, I didn't think that the Japanese adaptation would even have a sequel, so when the movie and sp was announced I was very delighted.

So the case that haven't appeared in the jdrama made appearance in this sp, which was the case of a woman who was supposed to be dead end up actually still alive. It's interesting to see how the case was rewritten in the sp to be set much later than in the original. So instead of this case being the origin as to how the secret evidence of corruption came to light, it end up becoming a way to reveal the truth of the death of one of the corrupt officers.