Nana Houzouin is Shinji's ex-girlfriend; their relationship concluded six months earlier due to Shinji's lack of passion stemming from his sexually different preferences. Despite separating, they maintain a friendship. Nana remains determined to reignite their romance, periodically making advances toward Shinji while harboring persistent, strong feelings for him.

When Shinji abruptly exhibits violent aggression toward her, Nana is initially rendered speechless and shocked. However, her enduring emotional attachment overpowers this initial reaction, compelling her compliance with his actions. This loyalty ultimately transforms her into his accomplice, as she assists him despite the circumstances.