Koizumi, Itsuki

古泉一樹

Itsuki is the final member to join the SOS Brigade, having been recruited by Haruhi as a "mysterious transfer student."

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Itsuki maintains a constant smile and always speaks in a formal, polite manner. He also tends to give long, detailed explanations, usually accompanied by exaggerated hand gestures. Itsuki has confirmed to Kyon once that his outward personality is merely an artificial image he fakes in accordance with Haruhi's impression of him, and he hints that his true character is quite different, being "less pleasing" in the eyes of others. However, maintaining his casual, constantly smiling self is vital for keeping Haruhi's mentality balanced.
Among the three Brigade members, Kyon is the least fond of Itsuki. He often finds himself annoyed by Itsuki's plastic smile, his willingness to acquiesce to Haruhi's outrageous schemes, his playful teasing, and his various forays into psychological and philosophical theories (e.g., the omphalos hypothesis, the Anthropic principle, etc.). He is also distrustful of Itsuki's intentions, comparing him to Yuki Nagato when it comes to deciphering his expressions. Itsuki's fondness for speculation often leads him to produce explanations for situations involving the SOS Brigade, its members, and related events. Ironically, Itsuki can only share his theories with Kyon and also enthusiastically plays different kinds of board games with him to pass the time, despite losing all the time, although Kyon suspects that he may be doing so on purpose.

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