So, MC has convenient plot device genetic disease and manga Japan governement, in all of it's lack of ethics and blatant breach of international laws of all kinds, says nothing to the parents or the ill person and uses their knowledge of that fact to blackmail a potentionally unwilling minor person to a not exactly legal shotgun mariage for eugenic reasons ...
Seriously, sometimes I wonder if the authors pause even for a minute to consider the implications of their drama-inducing plot devices. This manga had always a backdrop of totalitarian governement behind, but this plot tumor ups the issue quite higher than it was