Misako Ayukawa, a woman in her 30s, is an English teacher with ironically poor English skills. She values herself over her students and money over love. She displays arrogance in front of her students, but acts pleasantly around everyone else. However, Misako possesses a brilliant mind for solving puzzles. Motivated by the possibility of rewards and treasure, she ends up tackling various cases on the weekends along with three of her top students.