If one of you makes a mistake, then overcome it together. If one of you is happy, share it with the others. Joy, sorrow, anger, love...are shared among the five of us...in five equal parts!
|― Rena Nakano|
The "Gotoubun Principles" is first mentioned: the Nakano Quintuplets are supposed to share every emotions (joy, sadness, anger, love) with each other and split it equally.
The Gotoubun Principles are passed down from Nakano Quintuplets Grandfather.
- Chapter 12: The sisters describe the Gotoubun Principles for the first time.
- Chapter 50: The sisters give up their old apartment so they can be with Fuutarou. They will be alright as long as the five of them are together.
- Chapter 56: Despite only Yotsuba failing, the other sisters willingly transfer schools with her. This is due to the value of "being together as five" from their mother.
- Extra Bonus Comic of Volume 5: Due to the game bought by Yotsuba not allowing 5 players, Nino suggests buying 4 more consoles so they can play together.
Relevance to the Story
The principles is shown to stabilize and keep the relationship among the quints in check.