Originally Posted by
Ryllharu
SPOILERS BELOW:
We get to see Hachi's young daughter in the first part of the final episode. She wasn't named Sachiko, rather Satsuki, and is very clearly Takumi's child. Hachi has come to some semblance of settling her feelings for Shoji, but is still hurt over betraying Nobu.
The biggest point of the time jump is to reveal that the entire series has been a flashback. This should be obvious from the narration dialogue at the beginning and end of most episodes by Hachi or Nana. The whole series takes place in 2001, and the "time jump" parts in the final episode are in modern day. However, by that time, Nana and Hachi have well settled their feelings over their abrupt breakup, Shin has become and man among men, Hachi has become more mature (to a point), and Yasu....looks exactly the same.
The largest question is what happened to Nana. This part is left out, as her issues are only starting to be revealed in the main plotline. All we know is that she's not anywhere close to the others, ran away somewhere, and hasn't contacted anyone for a considerable time. A major part was left out of the Present Day material, but that would of course only make it that much worse of a cliffhanger.
End spoilers