I really like pencil scribble artstyle, it really complements the atmosphere of the game/story that you're telling. This is really unique, as I don't see this kind of artstyle that much. I was hoping there would be more exploration beside the library before you talk to Jonathan, because the art is just so unique!
During the mini-game where you fill in words, my first intuition was to drag-and-drop the word to fill the blanks. But it is not drag-and-drop and player must fill the blanks from the start of the sentence sequentially. My little suggestion here is to have a little cursor showing which blank is about to be filled by the next choice of word.
But since the sentence is fairly easy, I didn't make any mistake for the mini-game. I do wonder what will happen if you construct the wrong sentence...
<SPOILER for those who haven't played the game>
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There is also a little grammar sentence mistake when the two are walking together from the boy's perspective. If I recall correctly, he mentions her walking speed being very slow and the grammar mistake is quickly notice-able.
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<End of SPOILER>
Overall, this is a short and unique visual experience! I wish to see more of the game. There is definitely a potential of expansion, so hopefully you can build out the narrative into a full-fledged story!
Note: I was playing the browser version as I am running linux on my PC, so there may be more content in the downloaded version.