Although I usually stay away from mystery genres, I decided to comment on your plot, because I read the whole first post. .___.

I agree with some comments, the plot its too normal for its own good. Even though I may not know how fluent can Japanese students be at English, it just seems to me, from the plot, that Maemi does not actually suffer from the language struggle of coming from Japan, where very little is written and spoken in English to North America where everything is mainly written and spoken in English. My point is that you should make it clear, at least in the summary.

Also, it makes little sense why the father who abandoned her suddenly appeared after her mother's death. Plus, becoming her guardian, once more, at every cost possible but despising with all his being.

Since this is for a shoujo/josei manga, you should at least lighten up her personality, or at least make her father be one of those happy-go-lucky persons, and make the evil character who tortures her be her older brother.

I agree with Sarah00891, she makes a good point. nods

"Beware How You Take Hope From Another Man."

interesting plot :]
i wish to hear more about the diary and the mystery part.
sunny sounds like my character.so overall, your story is i would read. 😃
hopefully, i see this in the bookshelves of a bookstore.
good luck~