Runa is a girl of a very petite posture, looking rather youthful in comparison with other members of the Student Council. She possesses quite a light complexion, long platinum blonde hair with short bangs, split in the middle of her forehead and purple eyes.
She wears an orange rabbit kigurumi over the Hyakkaou Private Academy issued uniform; a red blazer with black trim lining the cuffs and collar, a white button-up dress shirt, a dark pleated skirt, a tie and white and black striped stockings, as well as the academy's issued footwear, brown-colored loafers with black soles. She has light pink painted fingernails and is often seen with various different lollipops sticking out of her mouth and playing games (Pink Playstation Vita in anime, Nintendo Switch with red and green Joycons in live action). She has orange lip gloss on.
Runa comes across as a cheerful, enthusiastic, and very charismatic individual, especially during public broadcasts. Unlike other members of Student Council, she is seen not taking her role too seriously, being known for eating snacks and playing video games during Student Council's deliberations, and not caring so much about school's issues.
However, despite looking friendly and innocent, Runa possess a streak of cruelty and tends to get bored very easily, which may indicate sociopathic tendencies. Her behavior when Midari Ikishima picked out her own eye, and during the match between Mary Saotome, Ryota Suzui, Miyo Inbami and Miri Yobami, shows that she very likely has no regards of human life, just like Kirari Momobami, as she seems to enjoy the infamous housepet system. A great example of this is when she humiliated Mary who confronted her about the case of her Lifeplan Schedule, telling her that she quickly needs to boost her skills in pleasing men. Nevertheless, a fairplay is still extremely important to Runa as she is able to put aside her ideas to keep gambling matches as fair and neutral as possible and any attempt of cheating is completely unacceptable for her.
Kakegurui - Compulsive Gambler
Runa is often seen alongside the president, managing stuff. Most of the time she makes a quirky remark or joke about the situation. She arrives with Kirari Momobami and Ririka Momobami at Yumeko Jabami's gamble with Yuriko Nishinotouin. Runa notes how pale and scary Yuriko looks. Runa also tells Mary Saotome about her life plan. The person she has to marry is a filthy lolicon, but it could be worse. She then laughs Mary off and tells her to practice pleasing a man.
She keeps on playing games in the council room and is amused to inform everyone that Yumeko wants to gamble with Kirari. When Midari Ikishima suddenly jumps up, she got scared. After Kirari left the school and the Council was troubled, she told everyone that Kirari would become a housepet if she lost. She most likely sent the torn up fan letter to Yumeko, so that Yumemi Yumemite's career could be destroyed. Kaede Manyuda wanted Yumemi to win so the second-years would become more powerful. Likely, Runa didn't want that and tried to frame Kaede, so that both of them would be beaten at the same time. She probably also did this in Kirari's interest. She frequently calls Kirari (actually Ririka) and tells her about how things are going down at the academy.
During the concert, she states how everything seemingly goes according to plan, but everything could crash down at any moment. When Kirari reveals herself as the vice-president, even she is surprised. During the Tarot game, she also acts as the dealer. When Mary notices which card the joker is, Runa warns her not to say a peep or the game will be ended and Yumeko automatically loses. She also insults Itsuki after she thinks Kirari could be cheating. After the game, before the others can take a look at the marked card, Runa confiscates it, leaving it unknown. Later she calls Ririka, telling her about the recent events.
Runa acts as head of the Election Committee where she oversees the entire event and tries to keep a neutral position. However, this is tested as the Momobami Clan take down each Student Council member. She also moderates the broadcasts of the election, announcing which players are in the lead, and explains the rules altogether. The committee's motto is absolute neutrality. But that is often tested, when the student council is endangered by the Momobamis. Ruri Fuen informs her of Yuriko Nishinotouin's defeat at the hands of Miyo Inbami and Miri Youbami. She gets quite annoyed, because she believes that there was cheating involved.
She is also present as the dealer during the Nim Type zero game with Yumeko Jabami and the others. Runa doesn't trust Miyo, especially after she had beaten Yuriko. She confronts her about having beaten her "fair and square". Runa then explains the rules and also warns them about the serve chips. She prompts Ryota Suzui to tell her a number between 10 and 30, so she can shuffle the cards randomly. When Yumeko gets poisoned, Runa tells them that she is unable to do anything since the poisoning has happened before the game starts. According to her, she has no influence on anything before the actual game. Runa is impressed by how fast Ryota agreed to Miyo's dangerous rules.
She again shuffles the cards and hits the gong to start the second round. When Mary tells Ryota to show his cards, Runa intervenes and says its prohibited. She adds though, that it's not forbidden to "accidentally" drop your cards. Runa shows content, with Mary Saotome tricking and eventually beating Miyo. She is proud of Mary for noticing the shuffling pattern.
She was also leading the live show between Yumemi Yumemite and Kawaru Natari. Before the show, she also got an autograph from Kawaru. She explains the rules to the audience and declares Kawaru the winner of the singing contest. During the second round, she was asked to try a bite of the spicy macaroon. Runa instantly ran off, screaming for water. She was impressed the others could even eat the whole macaroon. She also had the idea for the game of the third round and explained it to them. After that game, she counted the number of cards and announced Yumemi and Yumeko as the winners of the whole game. During the second broadcast, she once again announces the current top players in the election. She is excited about Yumeko's invitation for Kirari to gamble. She then tries to stop Sayaka Igarashi from attacking Yumeko, but is forced to put the live show on stand by.
She's soon very bored about the current ongoing gambles, since votes aren't flowing. But she is then very intrigued by the Votes Auction and observes it along with the Momobami's. She explains to them, how Rei Batsubami obtained all those votes for the auction. When Rin Obami organized a fake election gamble, Ririka Momobami saw through his plan and realized, that the present observer wasn't real. So she called Runa, who was listening in on the entire game. Right at the end, she bursts into the room and declares the game as valid and Rin out of the Election.
She scolds the imposter, but afterwards grants her a real observer hoodie. Runa also organizes the grand tournament. She is still annoyed at Rin and his trick, as it caused an uproar of mistrust towards the election commitee.
Runa is seen playing a video game with Aoi Mibuomi. The two are good friends and he jokingly mocks her for her size. When they finished the game, Sachiko Juraku enters and informs them about Mary Saotome, a very talented gambler. She is also seen excited about the school festival and is informed that a gamble takes place, thus she sends Inaho Yamato there.
In the spinoff manga, Runa is shown to be self-conscious about her childish looks, after being treated like a child by the other Student Council Members, who are younger than her.
In the live action, Runa is played by Natsume Mito. There are no significant differences in her actions.
Kakegurui - Compulsive Gambler
- A Boring Woman
- Slit-Eyed Woman
- The Women Who Became Livestock
- Tempting Woman
- Refusing Women (Flashback)
- Love-Dancing Woman
- The Dreaming Woman
- Selective Woman
- The Woman Who Bets Her Life
- Gambling Woman
- Gambling Women Again (Non-Speaking)
- The Women Of Momobami Clan
- Do Not Touch This Woman
- Communicating Women
- The Girl who Changes (?) The Connected Woman (?)
- The Hollywood Star
- The Woman By Her Side
- The Logical Woman
- The Woman Who Bears The X
- The Null Woman
Kakegurui - Compulsive Gambler
- The name Runa can be interpreted as "moon", which is influenced by the Japanese pronunciation of the Latin word Luna. However, since the writing is in hiragana, there is no real meaning.
- Runa (るな) is also a female given name.
- Runa's surname Yomozuki means "Hades, underworld, underground spring" (黄泉) (yomo) and "moon" (月) (tsuki/zuki).
- In Chapter 62, Ibara Obami calls Runa "Furry Girl".
- Natsume Mito (Runa's voice actress) is ironically the oldest member of the cast as she was born on February 20, 1990.
- "Look, it doesn't matter what you think. That decision has already been made and there are many ways to force someone to do what needs to be done, do you understand?" - To Mary Saotome