Ichiya Mokusaibashi, a tall and lanky high school student in Class 1B standing 183 cm tall with medium-length red hair, brown eyes, and a fair complexion, exhibits a distinct shift in personality. Previously laid-back, he transformed into an intensely devoted and expressive spouse after marriage, earning the "demon wife" moniker. He frequently wears headphones, sleeps in class, and is sometimes sketched by his partner during these moments. Despite receiving attention like birthday chocolates from female classmates, he shows no interest due to his marital commitment.

Unlike others assigned spouses, Ichiya proactively requested to become the wife of Tsukitsuka, a bandage-based creature, immediately after the main character's marriage. He displays pronounced emotional sensitivity regarding Tsukitsuka, visibly blushing and becoming flustered when the creature's bandages loosen or unravel. To personalize Tsukitsuka's appearance, he drew dotted eyes and a smile on the bandages. His relationship with Tsukitsuka is characterized by deep affection, protectiveness, and observers noting he appears "totally soft" and "absolutely in love" with the creature.