At some point, one of the characters says something along the line of "it's difficult to convey emotions using sign language".
I think this drama suffers from the same problem. The scenes that are designed to break our hearts and make my little sister cry just fall flat.

The very - very - slow pace doesn't help. Many times I felt like pushing the fast-forward button.

Some support characters become very quickly unlikable (especially Togawa - I felt pushing the super-fast-forward button every time he appeared on screen).

Bottom line: it's well made but something just doesn't work.