Come the end of the last episode of Tokyo Magnitude 8.0, Mirai had finally come to realise the truth about Yuuki's death - I'm sure it goes without saying that such a revelation would be difficult for anybody to handle, and thus of course much of this episode is taken up with Mirai's struggle to come to terms properly with everything that has happened.
That said, Yuuki's part in this story isn't done, as we see him urging a reticent Mirai on all the way until she reaches her home and is reunited with her mother in an inevitably emotional reunion - Indeed, perhaps you could argue that Mirai's mental state immediately after Yuuki's death was as much her own way of getting home to her family as it was simple denial to cope with losing him.
With the family fully reunited, we get to see just how important those bonds are when it comes to dealing with the grieving process, with open words and tears that can never heal the wounds of losing a loved one, but at least allow for all those concerned to accept what has happened. This is naturally more difficult for Mirai than her parents, and after some difficult times it's a visit from Mari that puts her in the right direction (although surely even Mari's story of when she lost her husband is not even close to being analogous to Mirai's grief) in what was as happy an ending as you could expect from a series like this - As we see Tokyo very slowly being rebuilt, yet with scars and memorials that will never go away, so Mirai learns to cope and carry on with her life despite knowing that the pain and feelings of loss will never entirely go away.
I think it's fair to say that I'm probably not the only one to be caught by surprise from the emotional impact of the final few episodes of the series - From depicting largely the technical details of a massive earthquake (albeit with an eye always on the human drama and impact), we really left all of that behind to focus entirely on the human tragedy of such an event. Perhaps Yuuki's death and our view of this from Mirai's eyes deviated from those technical scenarios, and perhaps it could have been shortened to some degree rather than keeping the "is he or isn't he" question alive for so long, but I defy anyone to say that they didn't shed a tear or two during these episodes - My eyes were damp from the very opening scene of this final episode, and it didn't get any easier from there.
Overall then, above all else I have to take my hat off to BONES for daring to take this series in the directions they chose to - They could easily have made it a pseudo-documentary with a focus on facts above all else, but as well as worrying about the details of the earthquake itself they also managed to zoom in on the real human cost of a natural disaster in a brave and very different fashion. They gave us a bleak view of a terrifying disaster, yet they also gave us characters that we could cry for and over as their lives fractured and were repaired just like the city around them, and those tears most certainly don't lie when it comes to discussing the quality of this series.