Inspector! It's Going To Be A Tough Case To Crack is the nineteenth chapter of Hinamatsuri manga series.'
Hina's classmates see Hitomi walk into a bar and, shortly after, their teacher enter the same establishment. The two assume the worst and decide to investigate. They enlist the help of their classmates Sayo and Hina to learn more about the situation. Sayo begins to question Hitomi and, after delighting in making her classmate squirm, realizes that she is hiding something from them.The four stake out the bar and barge in after seeing Hitomi and Nitta enter. While Hitomi tries to pretend that she doesn't know them, Sayo gleefully forces a confession out of Hitomi. Just as they leave the establishment, their teacher enters and they all realize that he does not realize that his favorite bartender is one of his students.