Congratulations for your first project. Although it was quite short, it was a nice reading. Amoto is a good mix of carefreeness and responsibility and Mikoto is very moe, even if a bit more development about her would make her still more likable. I love the association of these two kinds of stereotypes, it quite reminds me Hideki and Chi in the anime Chobits.
From the technical side, there are some circumstances in this story where objects crash or people fall without being emphasized. I suppose you didn't want to use too many trembling screens (which would be annoying), but there are other possible effects. And I was somehow expecting that you would use a bit more some of Ren'Py's features, as the engine is mentioned at the very beginning of the novel. Note this is not a true criticism, only a matter of taste (I'm just fond of special effects!

).
Speaking of effects, a few sounds would have enhanced the reading without being too distracting. But since the sound cursors in the game preferences have not been disabled, maybe you've already planned it for a future release?
Concerning the plot, I perceived a small inconsistency about Mikoto's age. At first, the way she is described as a little girl and her childish attitude made me consider her like a twelve-year-old. But some of Amoto's thoughts made me realize that she must be older.
Amoto's considerations (when Mikoto takes a shower or proposes to share the bed) seem irrelevant to this story. I don't think he can feel this kind of temptation as the age difference between them is apparently too big. Moreover, their friendship appears in the end closer to a fraternal love than a romance.
I was quite sad that the story ended so quickly. I wished it would have been a bit longer. Unless you're planning a sequel
*HINT HINT*, there's a question that remains unanswered:
Mikoto's hesitation to let Amoto alone doesn't explain why she didn't returned sooner. Carefreeness seems a cheesy justification (it's quite unlikely that she could return to Engrald from the beginning but had just forgotten that possibility). It should be possible to find a more convincing reason.
When she's about to leave, my feeling is that I miss information about her backstory. Does she have any other reason to stay? Is life in Engrald so wonderful? Does she have a family? Strangely enough, Amoto only mentioned that her friends would miss her, as if she had no relatives... Thus, I finally wonder if Amoto is very wise to persuade her to go back home.
Keep up the good work, I look forward to seeing what you'll bring next.
