Isami is taller than his twin brother, Takumi Aldini, with brownish-black spiky hair combed backward. He is usually obese, with small eyes and sharp, shark-like teeth that appear when he smiles or laughs. When cooking seriously, his eyes turn white, and his face darkens.

During the summer vacation before the 43rd Annual Tōtsuki Autumn Election, Isami lost a significant amount of weight, making him look very similar to Takumi, though his hair remained wild and voluminous. His eyes became sharper, and his teeth lost their pointed look. According to Takumi, Isami tends to gain weight in winter and slim down in summer. After the Stagiaire, he returned to his heavier form but later slimmed down again during the Beach Exam and BLUE, maintaining that fit appearance in Le Dessert.

Isami and Sōma discussing about Italian egg dishes

Unlike his fiery and competitive brother, Isami Aldini is calm, good-natured, and easygoing. Though more relaxed, he shares Takumi’s deep passion for cooking. Isami often laughs at Takumi’s overly serious or dramatic behavior, especially when his brother’s words are misunderstood. He also enjoys teasing Takumi during their friendly competitions, whether in cooking or casual games. Despite their playful rivalry, the twins share a strong bond, and Isami always does his best to support his brother.

Beneath Isami’s cheerful personality lies a quiet sense of pain and insecurity from his childhood. While he excelled in many areas, the kitchen was the one place where Takumi consistently outshined him. No matter how hard he tried, Isami could never quite catch up, which led to a deep-seated inferiority complex. Still, Takumi reassured him that he was essential to his success and that they were strongest together. After witnessing Takumi’s defeat in the Quarterfinal Shokugeki, Isami resolved to become stronger so that he could support his brother and ensure he would never lose again.

Born into a Japanese Italian family, Isami grew up in Italy alongside his twin brother, Takumi. During their childhood, the two worked at their family restaurant, Trattoria Aldini, under the guidance of their father and uncle. Although Isami excelled in many aspects, Takumi consistently outshone him in the kitchen, earning praise from customers who often requested dishes made specifically by him. Feeling envious, Isami once attempted to replicate one of Takumi’s dishes, but his father scolded him after the dish’s flavor fell flat. Tearfully, Isami apologized, admitting that he only wanted to be as skilled as his brother. Takumi comforted him, telling him that his own cooking only shines when Isami is by his side. From that moment, the twins made a heartfelt promise to grow together, improve their skills, and one day make Trattoria Aldini the best restaurant in Italy.

As time passed, Isami matured into a capable chef and became one of the restaurant’s key members. Recognizing their talent and potential, their uncle suggested that the twins attend Tōtsuki Culinary Academy to refine their abilities further. Though Takumi was initially hesitant, Isami encouraged him to take the opportunity, eager to test their skills at the world’s most prestigious culinary school. The brothers accepted the challenge and were soon admitted to Tōtsuki’s middle school division, where they excelled and advanced to the high school section, ready to take on new rivals and continue pursuing their shared culinary dream.