Sayaka Igarashi is a supporting character in the yuri series Kakegurui. She is the secretary of the Student Council and the personal assistant of Kirari Momobami. A very intelligent and serious girl, who deeply cares about the school and Student Council. She worries a lot about what happens to the school. She have dark violet waist-length hair that is kept in a side-ponytail.
- During middle school and her first year in high school, Sayaka was a shy and nerdy girl who's spends her time only on studying. Despite being the one with the highest grades in the entire school, she was pretty unpopular and didn't have any friends. Two years before the Yumeko Jabami's transfer, Sayaka witnessed a gamble match between the former Student Council President and a first year transfer student named Kirari Momobami over a Student Council President position. Sayaka was impressed by Kirari's victory to the point where she applied her CV to the Student Council in hopes to become a personal secretary of Kirari, now the Student Council President. Finding Sayaka interesting, Kirari agreed to hire her, giving her a little makeover in the process
- She is endlessly loyal to the Student Council President. She stated, that Kirari is her one true love and she would do anything for her. Kirari states, how much Sayaka is driven by logic. Her and Kirari's wildly different personalitys seem to be what attracts them to each other.
- She's jealous of Yumeko Jabami for capturing Kirari's interest and views her as a plague. Thus when something threatens Kirari or the school she gets very enraged quickly, like when She offered Kirari to eliminate every threat to her. But Kirari denied and enjoyed the thrilling situation and wanted to see more from Yumeko Jabami, which somewhat broke Sayaka's heart and she feels jealous of Yumeko. So, she called her out as a pestilence during the life broadcast and challenged her to a game of life and death. Kirari was excited by this and suggests the Tower of Doors. If Sayaka loses, she will not only die but she will also be a stranger to Kirari. This would be the worst nightmare of her and means she bet everything as Sayaka is determined to beat Yumeko. They have to solve the riddles in order to traverse through the tower. Sayaka quickly figured out the first solution and advanced one floor deeper. She was even at the first floor quicker than Yumeko. When Yumeko also appears, Sayaka has to held back laughter. She believed to have totally overestimated Yumeko. She was still determined and climbed the Tower in the perfect time. But Yumeko was already there, because she figured out how the tower worked. This meant Sayaka lost and had to jump. She was absolutely crushed. She chose one of the outer doors and subconsciously took the one, whose answer is 5, because the Tower had five floors. She stated her love for Kirari one last time and jumped. She already accepted her death, but Kirari jumped after her. Sayaka was terrified, thinking Kirari would now die too. But they landed on a safety mat. Kirari laughed and Sayaka was still shook. Kirari proceeds to tell her, that she is absolutely fascinated by her and how she acts only logical. Kirari then again asks her to become her secretary, since they are now strangers. Sayaka has now learnt, that she will never be able to truly understand her, but that is exactly where their feelings come from.