Available formats: physical / ebook / audiobook / full furigana
Summary - Japanese
私、宮美（みやび）三風（みふ）。 両親も親戚もいなくって、ひとりぼっちの小学校6年生……だと、12年間ずっと思っていたのに！ なんとある日、四つ子だったことがわかったの！！！！ 顔も声もまったく同じ女の子、 一花ちゃん、二鳥ちゃん、四月ちゃん。 それぞれ別の場所で孤独に育った私たちは、これから四人、一つ屋根の下で暮らすことになった。だけど、四つ子だけの生活は、大混乱！ その上、育ってきた環境の違いが思わぬすれ違いを生んで…？ みんな同じで、みんな違う！ キュートな姉妹生活、始まります！ 第６回角川つばさ文庫小説賞【特別賞】受賞！
Summary - English
I’m Miyabi Mifu.
I don’t have any parents or relatives—I’m a lonely sixth-grade elementary schooler with no family … or at least, that’s what I’d believed for all 12 years of my life!
But then one day, I discovered something unbelievable… I’m actually one of quadruplets!!!
Girls who look and sound exactly like me—Ichika, Nitori, and Shigatsu.
Each of us was raised alone in different places, but now the four of us are going to live together under one roof.
But life with quadruplets? Total chaos!
On top of that, the differences in how we were raised lead to unexpected misunderstandings…?
We’re all the same, yet all different!
A cute sisterly life begins!
Winner of the Special Prize at the 6th Kadokawa Tsubasa Bunko Novel Award!
Reason(s) for nominating:
This review from Biblio on Natively
High interest, low difficulty 
If you like human drama and slice of life this series might be a great pick for you.
We follow 4 girls who were orphaned and separated as babies. When they are 12 years old, they are re-united and start living together - on their own. The books are told from the POV of 宮美(みやび)三風(みふ) the third oldest/youngest? (I can’t rember :D) of the 4.
Each of the girls has had a different upbringing until now, so each comes with her own baggage. In the course of the series we get to know more about their past, what happened to make them orphans, etc. and the girls learn to rely on each other, how to deal with problems and how to be family.
It’s written for children, so the language is not very difficult (and it has full furigana, of course), but the stories are surprisingly interesting. Some of the topics are a lot darker and sader then the cover art suggests. There are some feels to be had.
I listened to the audiobooks, which I can highly recommend. The narrator does a great job.
- I think the drama elements could lead to lively conversations in the book club!