Dikutip dariterjemahan orang:

Summary of the right column: Mayu’s character design was originally suppose to be a girl, but Tsubaki-sensei thought her [Mayu’s] compatibility with the male characters, especially Mikoshiba, would have been bad so Mayu became a boy. [Reason being that] it would’ve been a bunch of high school boys being flustered in front of a quiet middle school girl. Also, as opposed to the more aloof eldest/second son, the daughter would’ve been the more intense (or high tension) character in the Nozaki family (taking after their father).
The center is female Mayu holding a sign saying “Originally female.” Text next to her says, “Female version appears quiet, stoic, and smart. Mayu.”
Captions under the picture: It’s too bad because if the idea was executed well, [Mayu] could’ve been the bishoujo (beauty) that this manga is lacking.
Column on the lower right:
Nozaki: My younger sister turned into a guy.
Mikoshiba: Ehh? It’s my fault?

Karena Mayu ga jadi karakter cewe, Mikorin forever alone dong Eh salah Mikorin tetap punya Suzuki-kun.