As a disclaimer, I did not read the original novel of Raden Meikyuu prior to watching the drama so my views are entirely based on the drama. I do note that there are some differences between both versions e.g. Aoi was the eldest daughter in the Sakuranomiya family according to the novel but was the youngest son in the drama version but I won't be able to comment much unless I've finished the novel.
Before sharing my views on this drama, here's a summary of the story. In case you haven't watched this drama and do not want to read the spoilers, please skip this section of the review.
The disappearance of Tachibana, a doctor who used to work at Hekisui and had been to see Iwao on the first day when Taguchi and Shiratori arrived, leads Shiratori to believe that this is related to the mysterious note he received. Subsequently, when Shiratori receives CT images of a dead person, it makes him realise that there is something dark going on within Hekisui. Meanwhile, Taguchi gets a feel of how important Hekisui is to the locals as he sees first-hand how the patients are full of gratitude for Iwao and his daughters Sayuri (Mizuno Miki) and Sumire (Kuriyama Chiaki). At the back of his mind, he does wonder if Shiratori's investigation will actually bring about tragedy to the locals if Hekisui is really found to be guilty of any wrongdoing and ceases to exist.
The second arc of the drama focuses on the issue of palliative care and euthanasia. Taguchi and Shiratori come to realise that some of the patients who had been critically ill and hospitalised in Hekisui died under sudden circumstances and always at the "right" time which leads them to suspect Iwao, his wife Hanao and Sayuri are committing euthanasia albeit with the consent of the patients. Sumire cannot believe this as she had not been fully informed nor allowed to participate in this all this while. Shiratori is especially against euthanasia which is still illegal in Japan and people who commit this, no matter what reason they may be doing this for. With Shiratori getting closer to the truth and on the verge of stopping the Sakuranomiyas from helping one last patient to die under painless conditions, the patient changes her mind thus leading Iwao to know that all is lost. In order to prevent his daughters from being implicated, he decides to commit suicide with Hanao. Just when they are about to set fire to the Raden room which is where the euthanasia incidents took place, Aoi begs his parents to take him with them. Before Taguchi and Shiratori can stop them, the trio are engulfed in flames thus bringing with them the existence of Hekisui. Sayuri is arrested for her involvement in the euthanasia cases while Sumire suffers injuries and becomes the sole survivor in her family. At the end, even though Shiratori managed to stop Iwao and his family from continuing with the euthanasia killings, the outcome turns out to be beyond what he imagined as he never thought that Iwao would have chosen suicide so as to absolve his daughters of the responsibility.
Another key factor which made the story more engaging was the cast. It was such a thrill to see the constant confrontations by Shiratori to Iwao where the latter remained unruffled no matter what Shiratori accused him of and he always had a ready answer to counterattack. Sayuri's response to Shiratori's incessant and somewhat overboard investigation was between that of her father's and younger sister's responses because she could be cold and displayed no reaction at times but would get worked up in some instances. Sumire, in contrast, was the hot-headed one who displayed her dislike for Shiratori very openly. This would have meant that Shiratori's relationships with the Sakuranomiya family in general was not favourable terms.
As for the key theme of euthanasia which the drama was heavily focused on, I think there is no attempt to show a more "dominant" or "supported" view with regard to this issue. It was more like both sides of the argument were laid bare for all to see and it was up to the viewers to decide which stand they support. I liked the fact that the drama did not try too hard to preach that one view was better or more correct than the other. Ultimately, it has to do with the individual and circumstances which he or she is in before we can say whether this action is in his or her interests. Iwao probably didn't set himself out to be God i.e. dictating who dies and when it happens but he was concerned about the emotional and financial burden on the families and the physical suffering by the patients. However, that still doesn't justify what he did because it was illegal. On the other hand, Shiratori is right in his own way because there is a potential for the system to be abused if doctors are allowed to induce death in their patients especially if the latter do not want to die prematurely. However, the way he went about investigating the case and how far he went to push the Sakuranomiya family to resort to suicide to solve the problem was probably what led to Sumire being so bitter about the loss of her family even though they did wrong in the first place.
And my ratings for this drama...
Story: 8 out of 10 (It would have gotten a higher score if the suspense aspect was tweaked to make it a bit more challenging and exciting)
Acting: 8.5 out of 10 (The main cast members did well in their own ways and helped to make the story more engaging)
Theme song/BGM: 3 out of 10 (The BGM was fine but the theme song was too forgettable and not very impressive)
Visual effects / Scenery: 7 out 10 (This drama looked like it was completed in summer or early autumn instead of winter when it was shown. As such, there were lots of greenery and nice scenes looking out to the sea since Hekisui was located in the suburbs of a seaside town. Within the hospital, there wasn't much to speak of except that spiral staircase leading up to the Raden room which was more noteworthy.)
Teamwork / Chemistry: 8.5 out of 10 (Great chemistry between the Batista duo and I liked the confrontational scenes between Nakamura Toru and Yanagiba Toshiro a lot. Not to forget, Yanagiba and Mizuno Miki actually looked convincing as father and daughter even though they are just 13 years apart in their real ages.)
Total: 35 out of 50