I wasn't even sure who the male lead was or if the author even intended to go there for the longest time. Someone who's more astute than me (or not using google translate) might catch it sooner. There was a small hint in the school arc, but I wasn't sure, since some authors like to ship tease. It wasn't until the late 800s, during the forced training trip, that the male lead became in-your-face obvious/established to me, but there were definitely some hints before this. It isn't as if there was any other likely male lead (except maaybe one, but they're too good as friends, I guess)... After this, there are some small developments now and then. Of course, it isn't for another few hundred chapters that he really starts making moves on her, but when he does, the romance speeds way up (relatively). It's pretty hilarious to read, since the MC has no immunity to romance related things. Once they get together, their lovey-dovey moments are so sweet, they give me cavities.
Keep in mind that the MC was physically 13 years old at the beginning of the story, and where I am now, she's like 15-16 years old, so it's not like the romance could/should have moved that quickly at the beginning anyways. She may already be an adult inside, but it's not as if anyone else knows that little fact.
As a side note, even though this story is relatively light-hearted, there is definitely a sinister vibe, too, since there are mad-scientist type body-experimenters running around scheming in the background who want to get their hands on the MC. Also, if anyone is worried she'll be stuck at school forever, she won't be, though she will be there quite a while; besides, she needed the leveling up and friend-making. It's interesting to note that even though she ends up gathering a bunch of strong, pretty boys around her, for some reason, it doesn't feel like a harem to me; maybe because it's obvious that they're all just good friends/family?
I swear the author loves being sadistic toward their main character. After a certain point in the story, anytime the main character becomes remotely happy, be prepared for her to get slapped into hell (not literally, but she might as well be there). You'll be a lot less appalled by the horrible things that happen to her. If it's not the MC suffering, it's the male lead or a side character.
The author also seems to enjoy torturing the readers as much as the main character. The storyline often drags; this trait of the author's writing persists even during the arcs where the main character is suffering. It's fine to want the readers to understand the horrible things the MC is experiencing, but when this goes on for tens and tens of chapters, I just want to bang my head into a wall several times. Some people probably enjoy this type of writing, but I find it unpleasant.
So with all that, why did I rate this 4 stars? Well, I read it this far, didn't I? There's probably something I liked about it enough to stick with it so long despite all the tragedy. The story can be pretty interesting if you can get past all that. Besides, a little bit before where I am now, things finally lighten up again. Yeah, that's like ~1000+ chapters (the turning point of the story into a swamp of angst is around ch.1000ish) of huge misunderstandings/tragedy, but at least it eventually stops. For now. Haha. Who knows if the author will put us through some more of that later... There are in-universe reasons for why the MC suffers so much, but I still think it's just an excuse for the author to torture their MC and us. Hahaha.
Also, even though I say it's like 1000+ chapters of angsty suffering, it isn't like extremely horrible things happen that whole time. It'd be more accurate to say that usually one big misunderstanding/horrible situation is ongoing for awhile as a backdrop to the other things happening, then that ends and another horrible situation happens and is ongoing, etc. Once in awhile, something more extreme on the horrible-and/or-tragic-events scale will pop up. There ARE some more neutral or lighthearted moments to balance the mood a little, so you should enjoy those when you can.
Honestly, I probably only stuck with it so long because after reading about all the horrible crap that the MC suffers through, I just wanted to see her get to be happy for once without getting slapped into hell. I'm glad the raws are up to a point where things finally seem to be going okay for her.