And the Academy Award for "Most Unclear Relationship Status" goes to...
Seriously, what's with this manga. They are clearly already friends, with the walking home and eating together, etc. They are close friends if they are meeting family members and going to flower viewings on days off. They are a precious friend if you cry over the thought of losing them at the flower viewing. And we could have ended the manga with the hand holding at the park already.
And now...she's just a friend?? DAFUQ??
The only thing that can slow this progression down any further would be introducing the childhood friend transfer student who knew him early on, before whatever event triggered his desire to be invisible. Mark my word, this is gonna happen...