Sexy high schooler Saki (Mihiro) works undercover as a yo-yo-wielding agent for the Japanese government. But as she investigates a prostitution ring at school, her see-through underwear -- part of her undercover "uniform" -- makes her a laughingstock. The only classmates who show her compassion are Takuya, a boy whose attention distracts her from her job, and Asuka, whose involvement in the prostitution ring leads to murder.