Although she is a police officer, she so hostile towards criminals that she often swings her sword instead of handcuffing them. Her behavior has been repeatedly criticized by the mass media, but as the sole Counter within the police force with the highest arrest rate, she remains untouchable even to her superiors. Her colleague, Kang Soyoung, also knows this and often tries to shift her responsibilities to Yumi. The two always quarrel with each other, but in the face of crime, they're partners