I'm pretty sure it was about Keita's first love. If you've seen some of the director's other work, he tends to be a little cryptic and throw in things that make you confused. I guess that "older sister" vibe was some more akin to love in the truest sense...but since it's a filler and it's Keita, it wasn't allowed to go anywhere.
I heard someone type my name and I came running across the country to find a computer with internet access.
...that and some idiots messed up our cable boxes and left us with no connection for a few days.