Ōizumi is an old man with a short stature. He has a bald head with light-colored side hair, which juts in every direction and noticeably thick eyebrows. In his youth, he had a full head of dark-colored hair.
During his appearance, he is always seen wearing a dark-colored yukata with a flower pattern haori over it.
Tōtsuki Autumn Election: Main Tournament
Main article: Tōtsuki Autumn Election Arc
Quarterfinals: Day One
Two weeks after the Preliminary Round, Ōizumi appeared as one of the judges in the Main Tournament. As Alice Nakiri and Sōma Yukihira unveiled their culinary equipment, the Quarterfinals began. Alice finished cooking her dish first and walked up to the judges, holding trays with transparent domes. Ōizumi is intrigued by the mist covering Alice Nakiri's dish which turned out to be a Temari Bento. However, he and the other judges were instructed by Alice to eat the sushi in a specific order, and were greatly impressed by each successive sushi. Sōma Yukihira followed up by presenting his Evolved Nori Bento. He and the other judges were surprised that Sōma used a layered bento box instead of a square container. As Sōma and Alice exchanged a few words, Ōizumi was constantly surprised with what each box revealed. However, he opened the final box to find mysterious black drops on the rice, which Sōma revealed as Nori Flavor Bombs. Tasting it made Ōizumi relive his excitement upon opening his lunch boxes during his childhood days. Finally, a Kudzu Sauce was unveiled and added to the Nori Bento. Moments later, Senzaemon Nakiri declared that Sōma was the victor of the match, much to the audience's surprise.
Shortly after, the second round between Megumi Tadokoro and Ryō Kurokiba began with the culinary theme: Ramen. As the match started, Senzaemon talked wtih Ōizumi about the history and popularity of ramen. When both contestants unveiled their seafood soup, he and the other judges left their tables to visit both Ryō and Megumi's kitchen areas. Ryō presented his ramen dish first, which he called Soupe De Poisson Ramen. The judges were overwhelmed by the strong impact of his dish. Afterwards, Megumi calmly presented her dish, a Kozuyu Chicken Soy Sauce Ramen, to Ōizumi and the other judges. As the judges concluded their judging of Megumi's dish, Senzaemon took out his brush to declare the winner.
However, Senzaemon did not strip for Megumi's dish unlike he did for Ryō and, in the end, Megumi lost the match. After the match, Ōizumi and the other judges made their way out of the arena, and were greeted by Erina Nakiri.
Quarterfinals: Day Two
Main article: Aldini Vs. Mimasaka Quarterfinal Shokugeki
On the second day of Main Tournament Quarterfinals, it was announced to the audience that the culinary theme of the third round was Hamburger. Ōizumi once again appeared as the one of the judges. Then, the contestants Hisako Arato and Akira Hayama arrived into the arena. As their match began, Ōizumi and the other judges observed both contestants as they revealed their ingredients. Hisako presented her dish first, a Soft-Shelled Turtle Hamburger. As the judges began to eat her dish, Senzaemon informed the crowd that only the judges who had eaten the burger itself could understand its power. Shortly after, Akira unveiled his dish, a Kofta Kebab Burger. While Ōizumi and the other judges was completely engrossed by the dish, Senzaemon had enough control of himself to fully pick out the secrets of the burger. After Akira lectured Hisako about their disparity, without a single doubt in the judges' minds, Senzaemon declared Akira as the winner of the match.
Before the fourth round began, a shocking announcement was made: a Shokugeki between Takumi Aldini and Subaru Mimasaka would be held. As the contestants made their way into the arena, Ōizumi and the other judges arrived at the judges' table, where it was announced to the audience that the match will be a full fashion Shokugeki with the theme being desserts. As the match began, Subaru and Takumi had the same ingredients, much to everyone's surprise.
Despite opposition from the other judges, Senzaemon allowed the match to continue as there was no rules that would admonish Subaru.
Subaru presented his dish first, an Improved Three-Layer Semifreddo. Despite the lack of originality, Ōizumi and the other judges could not deny that his dessert dish was delicious. Afterwards, Takumi presented his dessert dish, which Senzaemon named it a Lemon Curd Italiano Semifreddo because Takumi added lemon curd as a fourth layer. However, even with the change, Ōizumi and the other judges declared Subaru as the victor of the match, much to everyone's dismay.
Ōizumi reappeared in the Finals as a spectator along with other VIPs in the Culinary Industry.
- Ōizumi makes his first ever appearance at Chapter 64. However, his surname was only mentioned during Chapter 79 and his given name, Kakinoshin, was revealed only many chapters later at Chapter 153.