|Manga Debut||Chapter 3|
Rumina is shown to be serious and abides by the rules of Nangokuren High School. She is rumored to be super sadistic along with her sister, and has the will to attack anyone who breaks the rules. She is also loyal to Asuna, as she stopped attacking Rintaro, Tamao, and Kousuke because Asuna told her to. She's also willing to extort money for Asuna as well.
Rumina is an average young woman with shoulder length blonde hair with some covering her left eye, thin eyebrows, and a ribbon in her hair. She wears a red button down vest over a button down white shirt, a dark colored skirt with two yellow lines, black socks, and black shoes. She also wears a dark colored scarf and a yellow armband with the kanji for wind on her left arm. She also carries a sword.
After her clothes are ripped by Rintaro, she along with her sister wear school swimsuits.
Currently nothing is known about Rumina's past, except that she has enrolled at Nangokuren High School and became the chairwoman of the Disciplinary Squad along with her sister.
Rumina first appeared along with her sister Rurina, catching Rintaro and his friends watching students change. She and her sister then attack Rintaro and his friends, but can't hit Rintaro, until Asuna shows up and stops them. She then heads to the gymnasium, along with the other, to do an investigation. After they get there, she and her sister then try to extort money from Rintaro and his friends, but Tamao and Kosuke refuse. She and her sister then start to attack but are easily defeated by Rintaro and has her clothes ripped up. When Asuna shows up again, she then apologizes for trying to extort some money from Rintaro. Kosuke, and Tamao. After Asuna puts on a show and sells some merchandise, she then tells everyone else to leave after being informed that Ayane is on the way.
Later, Rumina is in the secret room with in the disciplinary squad club room along with Rurina and Asuna. After Rintaro and Ayane come in and find out that the squad is working for Rino, she then attacks Ayane along with Asuna and Rurina. After Ayane easily defeats them, the squad is disbanded.
Rumina was seen beside with Asuna, while reports about the Underwear Thieves's capture, Ayane gone solo and Marokichi's missing and she was told to search for Marokichi.
Rumina is shown to be fast and can completely synchronize with her sister for a joint attack. She also wields a sword with a kanji writen on the blade.
- Three Bodies, One Soul: Rumina, along with Rurina and Asuna, attacks an opponent simutaneously.
- Fang of Triple Wind: Rumina attack an opponent along with her sister Rurina, while Asuna launches two weights at the opponent.