Don't Call it Mystery Manga Omnibus Volume 5 collects volumes 9-10 and features story and art by Yumi Tamura.

The Hatomura twins are constantly switching places, and Totonou has been tasked with finding a way to tell them apart once and for all. But everything changes when he stumbles upon the family’s dark and dangerous secret. Totonou soon figures out how to tell the sisters apart, but by revealing it is he putting the girls in danger?

Then, when Detective Aoto’s daughter is kidnapped, he finds himself teaming up with Totonou to get her back. Things get complicated when the kidnapping’s connections to a cold case from eight years ago come to light…the very same case that earned Detective Aoto infamy for accusing an innocent man of murder! Can Totonou help help him find the right culprit this time around?