Itsuki Sumeragi (皇 伊月 Sumeragi Itsuki) is a supporting character in Kakegurui. She is a first-year student who belongs to the "Flower" class at Hyakkaou Private Academy and a member of the Student Council whose father is the president of a prominent toy company in Japan.
Itsuki has chin-length light caramel brown hair with bangs that are swept to the right and reaches her eyebrows with a green hairband in her hair, blue eyes and she has pink painted nails with star-like decorations on them (her nails are decorated with the suit of clubs in the manga), but she now currently has bandages around her bloody fingers after she ripped her nails out during the gamble against Kaede Manyuda.
She wears the Hyakkaou Private Academy issued uniform; a red blazer with black trim around the cuffs and collar that is decorated with gold buttons, underneath she wears a white button up with a black tie as well as a pleated skirt with black stockings that have silver stars on the sides of them along with a pair of brown loafers with black soles.
Itsuki uses her gambling skills as well as her immense wealth in order to get whatever it is she desires, whether it be a seat within the student council or even her collection of painted human nails. She is manipulative and business savvy and uses her own products in her gambles in order to promote them.
When she is first met, Itsuki acts very friendly but soon reveals her twisted and sadistic side. She has no problems cheating and painfully taking away the nails of others. She is devious and cared little for others and even seemed very aroused by the thought of getting the nails of people she likes. However she is actually quite cowardly and drops that façade if she herself is attacked. She is actually somewhat insecure and feels worthless without a high rank or power.
After she was expelled from the Student Council, she pretends to act very nice but actually just wants to use Yumeko for her own goals. However through her time spent with her and especially her experience during the Choice Poker game, she learnt to take real risks and be more brave. As a result she also became a kinder person and befriended Yumeko. Itsuki also has feelings for Kaede which also assisted in her learning to care more about others and realize that money and power isn't everything in life. He was one of the reasons she was so desperate to stay on the council and keep his attention.
Kakegurui - Compulsive Gambler
Following Mary Saotome's defeat at the hands of Yumeko Jabami, the student council members hear about these news. One of which was a current member of the student council named Itsuki Sumeragi, who with her riches as the daughter of the largest toy company in Japan, got the position. Itsuki showed excitement in trying to gamble with Yumeko.
During lunch time, Itsuki immediately followed Yumeko's trail in the school and somehow managed to get to her. She invites her to gamble with her, and while Ryota Suzui tries to halt Yumeko from gambling, she still wanted to gamble and accepts Itsuki's gamble invite. She invites her to play a game of "Double Concentration" in which the rules are fairly simple. 2 decks of cards will be used, making the total card usage of each game 104. Each player must then flip 2 cards of their choice in their turn. If they flip a pair of matching cards with the same suit and number, then they gain 2 points and the flipped cards are remained flipped open. If they flip cards that don't exactly match, then they lose a turn to the opponent. For their match, Itsuki places down 20 irregular colored chips which are worth 1 million yen each, making it a total of 20 million yen. For the betting, Itsuki uses all the 20 million worth chips, making their bet 20 million. Though Yumeko says she does not have the money, Itsuki assures her worries by saying she'll lend her 20 million.
Then, they begin to play. She wins the first round, even though both of them have a great memory. Yumeko really wants a second round but has no more money. So, Itsuki suggests Yumeko's nails as a bet. She shows them their nail collection, which she all got from people. She starts to act crazy. Yumeko accepts and Itsuki is sure she will win, since she has a trick up her sleeve where using her bag, some heat will reveal a pattern on her specially made cards that will disappear once the cards cool down. This makes her believe that she is unable to lose. However, Yumeko caught up on the trick and beats her. As Yumeko suggests to rip Itsuki's nails out, she cries. After her loss, she's expelled from the council.
When Yumemi Yumemite challenged Yumeko, Itsuki joined in to support her. She gifted her a chestnut cake and acted really sweet. But everyone knew, she was just trying to suck up to her. Then Itsuki admitted, that she needs her to get back on the council. Her father is a practical man and if she isn't powerful at the school he won't guarantee her a safe future. Yumeko has no problems with that and states they are friends.
Later when Yumeko challenged Kaede Manyuda, she was hoping that Yumeko would win. But then she needed more money and turned to her. She was hesitant at first but decided to lend her money. The bets got higher and higher. Itsuki knew that losing would mean her life was practically over. Enraged, she ripped off all of her nails and betted the amount of money her life was worth. After Yumeko ended up winning, she revealed that the two were planning this whole act in order to lower Kaede's guard. However, she didn't get back on the council after that.
She also observed during the Tarot Cards of Fate game. If Yumeko would have to leave the school, she wouldn't be able to get back on the Council so she was rooting for her. During the game, she and Mary noticed a nail polish mark on a card. The only card Kirari picked up was the Fool, which was the best possible card. But Runa forbid them from saying something to Ryota. They were nervous, especially when he announced he would pick a random one. But he won and they were very relieved. Through her experience with Yumeko, Itsuki changed for the better and she now has no colored nails, since she came to terms with her yearning.
Since Kaede Manyuda had bet his life plan, Yumeko Jabami received it, but gave it to Itsuki. It becomes apparent that she actually has feelings for him. She watches over him, as he lays in bed, still under shock. She goes on to collect quite a few votes during the election. She is also present during Yumemi Yumemite's battle against Kawaru Natari. She votes for Yumeko and Yumemi, but wonders if Yumeko would be alright with all this cheating. Itsuki is surprised to see, that Kawaru still won. After the show was over, she cheered for Yumemi and Yumeko after they did win.
Since she now owns Kaede's life plan, she looks after him, but he just tells her to leave. She then mocks him, but secretly just wants to motivate him to get his spirit back. She is shocked to see when he also plays the Greater Good Game with her, Yumeko, Miroslava Honebami and Ibara Obami. He says however, that he doesn't care if he wins. She is annoyed at his lack of will for anything and tries to somehow cheer him up. During the game Itsuki and Miroslava team up, but Itsuki betrays her, getting Miroslava expelled. She realized however, that Itsuki wasn't trying to win herself, but rather make Kaede win, whom she loved. Itsuki was embarrassed, but Miroslava promised to keep that a secret.
Itsuki won the game and received 100 votes from Terano Totobami. Rei then announces that Itsuki and Terano made a bet on the outcome of the game. Sumeragi bet that Kaede wouldn't get 40 coins. The reason was, that either way she would be happy. Would she be right, she got Terano's votes. If she's wrong it would prove that Kaede still has some gambling spirit in him. Yumeko states, that is simply self-deception, but it is better that way. Since Kaede got 40 coins, Itsuki has to give all her votes back to Terano. Kaede finds that stupid of her, but Itsuki declares him as her accomplice and grabs his hand. He realizes that she has been playing with her heart and not just her head. As she walks out, Itsuki announces that she retires from the election.
She hears from Ryota about what went on at the auction. She is astonished and relieved to hear that Yumeko won. Yumeko is meanwhile losing all her votes, but having fun. Itsuki reminds Yumeko again, that she should be more careful, after she asked Itsuki to gamble. She is later very excited when she sees Yumeko on the broadcast of the tournament and cheers for her.
In the spinoff manga, Itsuki is shown to be friends with Mary and the two girls often hang out together. In a chapter, she's tormented by nightmares where Yumeko wants her fingernails, but can't fully remember them, until Yumeko mentions the same subject in real life.
In the drama, she is played by Ruka Matsuda.
Kakegurui - Compulsive Gambler
- A Boring Woman
- Love-Dancing Woman
- The Dreaming Woman
- Selective Woman
- The Woman Who Bets Her Life
- Gambling Woman
- The Women of Momobami Clan (Non-Speaking)
- Communicating Women
- The Connected Woman
- The Hollywood Star
- The Treacherous Woman
- The Winning Woman
- The Null Woman
- The Woman Who Bears the X
Itsuki thinks that being with Yumeko, when she rises to power in the academy, will help her join the Student Council.
Kaede is Itsuki's romantic interest. She currently owns his life plan. They are very like-minded people.
- The name Itsuki means “that one" (伊) (i) and "moon" (月) (tsuki).
- Itsuki's surname Sumeragi (皇) means "emperor" in Japanese.
- At the end of Episode 12, Itsuki is seen with healed fingers and unpainted nails. However, in the second season, she still has bandages
- "Someone controls your life, so what? Put some wins under your belt and turn the tables. It’s no reason to give up your ambitions!"