名探偵 耕子は憂鬱 第01-05巻 [Meitantei Kouko wa Yuutsu vol 01-05]

The manga is set during the height of the Showa era, and centers on a little girl named Kouko who is in training to become a detective. She is hired by a notable family to find out who sent a death threat to the family's son Inugami, who currently resides in a dormitory in Tokyo. To this end, she moves in to the dormitory to begin her investigation, but she is bad at cooking and even worse at figuring out where to start with the case. [ANN]Note: Adapted from the author’s oneshot that was released in Hana to Yume 3/2020 issue. That oneshot added to the 1st volume as chapter 0.