Female Takeru emerges from a magical gender transformation accident during a school trip to a southern island. Shiria Ootsuka's Maken accidentally activates while Takeru trains intensively to control his own Maken abilities, an effort interrupted by the beach excursion. This activation transforms Takeru's physical form into a female version.

Initially, Female Takeru finds enjoyment and novelty in this state, engaging in lighthearted activities with female classmates like Haruko Amaya. These interactions leverage the tropical island setting, including beach scenarios and instances of nudity. However, this period gives way to unforeseen complications and challenges, revealing the situation extends beyond superficial enjoyment.

Attempts to reverse the transformation drive the narrative. Inaho Kushiya, known for experimental potions, devises a concoction meant to restore Takeru's original male form. These efforts instead trigger chaotic outcomes, worsening the predicament and fueling comedic, unpredictable events. Female Takeru's peer interactions shift during this time, particularly dynamics involving friendships, rivalries, and group activities centered on Maken weapons. The altered identity prompts new explorations of social relationships and situational challenges unique to the female form, while the series maintains a comedic and action-oriented tone.

The southern island environment amplifies both the comedic and adventurous elements of Female Takeru's experience. The tropical setting facilitates scenarios like beach combat, magical mishaps, and communal living that test group bonds. Identity and camaraderie emerge as underlying themes during the gender-swapped period, primarily serving as catalysts for humor and episodic conflict.

This incarnation of Takeru is confined to this specific OVA episode.