I really enjoyed this anime, though I will admit that Miu hard carries the anime despite the absolute menace she is. But therein lies the problem, many believe that she is an unreasonable brat, but honestly after finishing the anime and thinking back on everything I watched, I can't say I hate her for the way she acts.
As stated by Nobue at the end of Episode 5
"...she (Miu) is lonely too)".
I understand why she says that now, and I feel like was something that people just gloss over as they continue watching the anime. I found myself agreeing with Nobue, because of all the main cast, Miu has no other relationships clearly seen with anyone besides the main cast, not even her own parents. Her parents are never mentioned, seen, or referenced throughout the 12 episodes in the anime (unless I missed something.) The same can't be said for the other cast members. Matsuri is seen going on a vacation through a photo, where she states that her parents went with her. Ana's mother and father can be heard talking to her in her introduction, and her mother is also explicitly seen. Nobue and Chika obviously have each other, but we can also see their parents in the dining room at one time and even hear them talking. However, I can't think of a single moment where Miu's parents are seen, referenced, or even talked about by Chika or Nobue (her neighbors who are clearly close to her). She has no siblings, the adults around her don't want to deal with her (Nobue and even her teacher at times), and to me it seems like all she wants is attention, which is something that she doesn't seem to get a lot of.
It's a realistic depiction of how kids in reality act, and I feel is a welcome element in a comedy like Ichigo Marshmallow. I certain that when we were all kids, we had a time where we acted the same as Miu when we didn't get the attention we wanted. Luckily for many of us, we had adults that corrected us and gave us attention (i.e our parents.) I agree, sometimes her actions are just plain evil, but for a kid who wants attention and isn't much besides when she is being a menace, what other way will she act when no one is willing to correct her.
I disliked Miu relative to the other characters when watching the show, but I never really thought about her like this. We really do never hear about her family. She's a really well done example of a kid who lacks affention from the adults in her life and ends up acting out so that someone pays attention to her.
I understand where you are coming from, and I believe her being lonely was obvious, however! Lonely or not, what she did on ep4 can't be justified. I really hate her, I would kill her, if it happened to me. I understand she js a kid and all, however no matter how much you life sucks, you don't knoe about other people, you "rebel" / "revenge" shouldn't hurt other people.