Kaoruko Sajima is one half of a comedy duo with Aimi Yoshizuma, dreaming of Broadway fame, an ambition that cost them family acceptance. Together, they operate as self-appointed heroes of justice, Love Pheromone, undertaking part-time heroics. Their interventions, however, consistently cause massive collateral damage and urban destruction, terrifying the public and earning them a mistaken villainous reputation; they justify destruction with their motto "Anything can be done in the name of justice." These hero activities often sabotage professional comedy opportunities arranged by their career-focused manager.

Physically, Kaoruko possesses notably large breasts, contributing to her greater popularity than Aimi and frequently sparking Aimi's envy. This envy drives Aimi to subject Kaoruko to repeated, unsolicited groping, even during sleep. Within their partnership, Kaoruko typically adopts a more measured, rational approach, serving as the composed counterbalance (Blue Oni) to Aimi's impulsive, volatile temperament (Red Oni). Kaoruko's romantic interests lean toward younger males.

The duo employs coordinated magical girl-style transformation sequences, complete with signature poses and catchphrases. They pilot a shared Humongous Mecha for transport and combat, accessing it via unconventional means like slides triggered by toilet flushers in their home; Kaoruko's mecha features weaponry capable of unleashing missile barrages. A recurring theme involves their persistent societal misinterpretation, where intended heroism backfires, casting them as antagonists. Their journey intertwines themes of pursuing aspirations—comedy stardom or chaotic justice—amid financial struggles and societal rejection.