>>1160203Why didn't you explain that in the OP?
In regards to that, I don't know if it's true? The description on the Pixiv post from the artist advertising the manga's release says this, "オリジナル褐色ロリです、書店の予約が始まりました。 よろしくおねがいします!", where the first part just says she's an "original dark-skinned loli" and none of the tags say she's a borrowed character (there's a tag for this).
https://www.pixiv.net/en/artworks/78338326Best I've got is one of the comments mentioning another picture he drew a few months earlier with what looks like a grown-up version of her:
https://www.pixiv.net/en/artworks/76841873Once again, there's no "borrowed character" tag, but does have the original tag.
Conclusion: She's just the artist's OC. If you want a relatively similar character (sans dark skin, sorry), then maybe Latina from Uchi no Musume?