|Name in Japanese||高坂 佳乃|
|Romaji Translation||Kōsaka Yoshino|
|Debut (Anime)||Episode 01|
|Debut (Light Novel)||Volume 01 (Chapter 01)|
|Appears in||Light Novel, Anime|
|Voice Actor (Japanese)||Akeno Watanabe|
Yoshino Kōsaka (高坂 佳乃, Kōsaka Yoshino) is Kirino and Kyousuke's loving mother and Daisuke's wife. Compared to her strict and unapproachable husband, Yoshino is carefree and has a more positive way of supporting her children.
She is voiced by Akeno Watanabe.
Yoshino is a middle-aged woman with brown eyes, brown wavy hair and often wears comfortable clothing composing of collarless shirts and leggings.
Between the parents of the Kousaka family, Yoshino is the one with a more passive approach to parenthood. She is often in a positive mood and can be seen joking around with her children, particularly Kyousuke. She is aware of many things going on in her family, particularly Kyousuke's stash of porn magazines and Kirino's hobby, and helps keep the peace in the house. Despite this, she keeps Kirino's secret to everyone, although she uses Kyousuke's "interests" to her advantage at times.
She is also quite proud of Kirino's achievements, as it often becomes a topic whenever she is chatting with her neighbors.
In tense situations, Yoshino often prefers to stand aside instead of choosing which side to support and leaves the problem to those who are involved.
Yoshino is first introduced during the moment after Kyousuke discovered Kirino's DVD case. Noticing the unusual actions of her son throughout the house, she simply shrugs this aside and continues with her daily chores. She is later present when the DVD case falls into the hands of Daisuke. Instead of involving herself, she chose to leave the house to buy her husband some sake to calm him down.
- Despite being a housewife, there are moments where Yoshino seems absent in the house whenever Kirino and Kyousuke are around.