Yoshida-san, why art thou so cruel? Give us the best, most reliable friends we could count on, and force us to assassinate the last one. Why? Is it a lesson on how cruel the universe is to take all our friends away? Or a comment on the necessary strength to keep going forward without using the diary or new game+ to revive old cherished moments?
The block of text in the lower right of the third panel is the same as what's in the fourth panel (the notebooks are meant to be read from left to right). I included a note to make it more clear.
Also, notice in the first panel how Sakura's handwriting and use of Kanji improves with each volume.