Well I just finished up to episode six already with this drama, so I am now stuck having to wait every week for a new episode.
While the mysteries continue to be intriguing it is really the characters that shine in this drama. For a series like this if you do not have that connection to the characters to care about what happens to them then it looses a lot of appeal. But you do want Team Enomoto to succeed as it is easy to like them as they play off each other so well and are a joy to watch.
I think overall the series is still rather strong with a good idea of where it is going and how to keep a theme like a locked room interesting for the viewer. I really cannot wait to watch the rest, even though now I must since I have managed to catch up with it.