Eri Isezaki, a brown-haired, brown-eyed girl with a tsundere nature, balances sharp-tongued critiques with concealed affection. As a classmate of Takeru Arashiyama—the protagonist’s younger brother—she quietly nurtures a crush on him, often masking her feelings with mock disdain during group activities like trading card games. Her brusque school persona softens in private moments, revealing a sincere, attentive side. This duality peaks during a carefully planned weekend date with Takeru, where she prioritizes his enjoyment, meticulously crafting a warm, engaging atmosphere despite her usual prickly exterior.

Peers affectionately call her “Ebi-chan,” a nickname of unexplained origin. Standing at 1.30 meters, her petite frame complements her youthful charm. Born on August 22, her history before befriending Takeru remains a mystery, with no documented expansions of her story in other media.