This one is played in episode 7, around 19:50. The actual length of the piece is much longer. There’s a second ending to this first part, and then multiple ends to that one, and so forth and so on. This is just the blatantly subtle part that reminds me of this Hisashi piece from Spirited Away.
This the second piece, from episode 6 at 10:30. It kind of reminds me of the piano music from 5cm. It was weird though. Right after it was done, it repeated, but I was anticipating it to be in the parallel minor key. That would have sounded like this.