Blue Box - We see how Chinatsu spends her New Years with her grandparents.
After being asked by her Grandfather if she has a special someone in her life, her mind goes to Taiki and we get a bunch of flashbacks from the series so far.
Then the chapter ends with her Grandma telling her that her Grandpa confessed his love by saying that she was the person he wanted to see first thing when she got up. Which is...how Taiki & Chinatsu see each other now.