Koizumi, Itsuki

Seiyuu / Dub

Hasper, Kim· Japanese

Jeon, Gwang-joo· Japanese

Ono, Daisuke· Japanese

Yu, Zheng Chang· Japanese

Bosch, Johnny Yong· English

Graziano, Leonardo· Italian

Motos, Jesús· Spanish

Pascal, Benjamin· French

Summary

Itsuki Koizumi, a sixteen or seventeen-year-old student in grade eleven standing at 178 cm, serves as the Vice Commander of the SOS Brigade. He was the final recruit, brought in by Haruhi under the guise of being a mysterious transfer student. Koizumi maintains a perpetually smiling demeanor and speaks in a formal, polite tone, often accompanying his lengthy, detailed explanations with exaggerated hand gestures. He has revealed to Kyon that this cheerful exterior is merely an artificial persona adopted to align with Haruhi’s expectations, hinting that his true self is far less pleasant. However, he considers maintaining this facade essential for stabilizing Haruhi’s mental state. Among the brigade members, Kyon dislikes Koizumi the most, frequently annoyed by his plastic smile, his subservience to Haruhi’s wild schemes, his teasing, and his obsession with psychological and philosophical theories like the omphalos hypothesis and the Anthropic principle. Kyon distrusts Koizumi’s intentions, comparing his unreadable nature to that of Yuki Nagato. While Koizumi’s penchant for speculation leads him to offer explanations for brigade events, he only shares these theories with Kyon. The two also play various board games together, with Koizuki enthusiastically participating despite always losing, though Kyon suspects these defeats may be intentional.