Hiroi is an older woman with short hair that falls just above the nape of her neck in the back. Her eyes are commonly closed. She wears two earrings and wears a standard chefs uniform with a chef cravat and an apron.
As a follower of Azami's doctrine, Hiroi gives her full support and is kind to any student who follows his ideals, even encouraging them to persevere when they make a mistake during the exams. However, for those who rebelled against him, Hiroi has shown extreme ruthlessness, purposefully inflicting handicaps on them to ensure that they fail the exams. However, when the students managed to produce an excellent final dish, she was forced to admit that it was good and promptly passed them.
Hiroi was assigned to one of the halls for the first Promotion Exam. Among the students in her class were Erina and several rebelling students including Sōma, Megumi, Alice, and Ryō. She assigns the class to cook a salmon dish to be completed by the end of the day. The students quickly get to work using the ingredients prepared for them by the school. While most of the students receive good, fresh salmon, the rebelling students were given purposefully low grade, Hocchare, waste grade salmon. Hiroi taunted the students, telling them that if they were upset with the fish dealt to them, they were free to go out and secure their own salmon. Because salmon was out of the season and Tōtsuki's connection easily allowed them to secure all possible fresh salmon available, Hiroi laughed they showed concern, believing that they had no chance of creating a passing dish. She also approached Erina, telling her that soon, she will no longer need to worry about the rebel students will soon be gone, however Erina expressed full confidence that they will be alright. Despite her attempt at crushing their spirit, the students already had begun formulating a plan and left the room, declaring that they will soon return and make the best salmon dish in the room.
While the rebel students were gone, the other student began to finish their dishes, with Hiroi passing most of them since they had applied what they had learned from Azami. Among them was Erina who passed it with relative ease. With only thirty minutes left, the rebel student returned with a tokishirazu that was fresh due to brine method. Even with only thirty minutes to create their dish, the rebel students quickly crafted a Yuan-Style Grilled Tokishirazu and was able to force Hiroi to pass them, much to her frustration. To make matters worse, the other rebel students in the other room had achieved similar results.
That night, Hiroi was fuming that she had failed to get a single rebel expelled, however on the news, she received a notice that an impending blizzard was about the hit Hokkaidō, giving her a new sinister idea to take them down.