Benio Yonomori (夜ノ森 紅緒 Yonomori Benio?) is Kobeni Yonomori's older sister. On the outside, she is the talented student council president at high school, but in truth, she is a huge pervert and is an extreme siscon to Kobeni Yonomori.
Benio has long red hair, and brown eyes that sometimes appears a purplish color sometimes. She wears a pair of spectacles in school, but does not always wear them at home.
To her schoolmates, Benio is smart, athletic, and is extremely popular to the point where people are jealous of Mashiro since she tends to be showered with attention. Articles are written in the school newsletter about her achievements. She is presumably dedicated to her student council work as she leaves the house early to do it.
However, she can be possessive, especially of Kobeni. Benio also has an obsession with young-looking girls such as Mashiro and even Shirayuki. She frequently invites Mashiro to the student council room for tea and cookies, or other pastries.
She blames herself for Kobeni's accident, since she was supposed to go up into the mountains with their grandfather instead of Kobeni, but she asked him to bring her along instead since she wanted to play with some friends.
Benio is Kobeni's elder sister. She often dotes on Kobeni, to the point where she occasionally seems to be obsessed with her. She even claims that she would have taken care of Kobeni until she was old, and would never have allowed her to leave the house. However, Kobeni seems to have gotten used to Benio's obsessive behavior.
Benio also has an obsession with Mashiro due to her size, much to the younger girl's chagrin. Mashiro will often try to run away from Benio, or will hide behind her elder brother or Kobeni when Benio begins to scare her. Mashiro, as a result, acts coldly towards Benio and turns down any suggestion or offer the latter brings up.
Nadeshiko keeps Benio in-check whenever her behavior is unacceptable, often by hitting her with a book. Benio often calls her to talk about trivial matters, such as the dream she had about Kobeni and Mashiro. Since Nadeshiko deems such things unnecessary, she sometimes cuts off the calls. She is also the vice-president of the student council.
Konoha idolizes Benio, much like majority of the school. She is also the secretary of the student council, which Benio is the president of.
Benio doesn't like Hakuya due to her obsession with Kobeni and doesn't want him to take her away OR ANYONE. Despite having fits about his relationship with her younger sister, they can agree on the same things whenever it comes to Kobeni(As claimed by Mashiro).