Undercover Investigator~~Rules of the Fallen Yuka Arai

``We know that there are investigators among them, so let's test your loyalty. Now, drink this poisoned wine!'' Yuuka, a hidden investigator, and her junior are in a difficult situation. Shibata. Kill me! In order to attract the enemy's attention, Yuuka sacrifices herself and entrusts Shibata with the mission... *The contents may differ depending on the distribution method.