Takumi's partner and sometimes rival in the kitchen, Isami is Takumi's younger twin brother. In their lives, the brothers are often seen together, whether in the kitchen or any place they go. Despite their different personalities and cooking skill level, both brothers share a very strong bond and dream of making Trattoria Aldini the best restaurant in both Italy and the world. Takumi is very protective of his younger brother and would do anything for his younger brother's sake, and cannot forgive those who insult him. While Takumi is the older brother, Isami seems to be the more level-headed of the two, usually seen dragging his brother off when he embarrasses himself or laughing him off when he goes into a tear about someday beating his rival, Sōma Yukihira. After winning the Régiment de Cuisine and becoming a new member of the Elite Ten Council, Isami hugged Takumi to congratulate him.
The head chef of the Trattoria Aldini, Takumi's father is Takumi's idol and also the one who recommended him to enroll into Tōtsuki Culinary Academy to polish further his skills. Behind his recommendation is his concern about Takumi's achievements. Even Takumi's skillful cooking did earned praises from various customers, he deemed that popularity would make Takumi stop learning and only his encounter with another rival would make him see his weakness. Prior to his sons' departure, he gave each a bottle of Aldini olive oil as a memento and good luck charm.
The owner of Trattoria Aldini, Takumi's uncle also recommended him to enroll into Tōtsuki Culinary Academy to polish further his skills.
Tōtsuki Culinary Academy: Allies and RivalsEdit
Like many students, Takumi became determined to defeat Sōma following Sōma's infamous entrance speech. Having also worked in a restaurant since his childhood, Takumi deemed Sōma his rival, although they would not meet in person until the Tōtsuki Friendship and Rapport Training Camp. Since then, Takumi has had a largely one-sided rivalry with Sōma, constantly seeking his attention in hopes that he will notice his presence. He is constantly annoyed when Sōma doesn't notice him and always observing him and wondering about his whereabouts, showing he cares for him or at least making sure that no one else will beat him before he does. Beyond this rivalry, the two have a friendly, brotherly relationship with one another.
While Sōma understands Takumi's drive and passion, he still does not always see Takumi as a rival because of his apparent need for contests, making almost everything they do into a competition and acting all high and mighty as well as dramatic about it. Because Sōma often disregards Takumi's taunts or challenges by treating him like a friend or sometimes a sidekick, this leaves Takumi both frustrated and embarrassed.
Through his heated yet friendly rivalry with Sōma, Takumi befriends almost all the Polar Star Dormitory students.
Takumi's first opponent for the Autumn Election Main Tournament was Mimasaka and also his first Shokugeki opponent. Before their match, Takumi found him sneaking into his room and told him to leave. However, an insult from Mimasaka about Isami enraged Takumi and prompted him to quickly accept Mimasaka's 100th Shokugeki match. During the match, Takumi realized Mimasaka was mimicking his semifreddo and improving upon it. Without time to start over, Takumi tried to turn the tables by making his improved Semifreddo with his fourth layer. Sadly, Mimasaka predicted this move and adjusted his recipe to compensate, defeating Takumi 5-0 and forcing him to give up his prized mezzaluna.
After Soma defeats Mimasaka, Takumi declared that despite his previous defeat, he will be victorious in their next battle by going 10 to 100 steps further than Mimasaka's single step ahead. This declaration made Takumi gain a new rival besides Soma.
Although they haven't had that much interaction in the series, Takumi and Megumi are shown to have known each other well. Slight evidence is shown when Megumi panics and starts to write "person" on her hand and Takumi states that it was too early for "that ritual". Also, Takumi showed a sincere relief towards Megumi after she shared the same motivation to defeat Central as him. The two become closer during their time preparing for the Regiment de Cuisine.
At some point, Takumi realized that Eizan was the mastermind responsible for rearranging Takumi's match against Mimasaka instead of Sōma, which was a part of Eizan's dirty tactics to get rid of Sōma for interfering his ambitions.
After the Regiment de Cuisine's 2nd bout is over, Takumi decided to choose Eizan as his opponent, determined to pay back for what happened in the Autumn Election through his cooking battle. Knowing Eizan's tendency for underhanded tactics, Aldini looked into Eizan's Shokugeki's, allowing himself to foresee Eizan's attempt to sabotage and adjusting his dish to prepare for it.