Hideo Murata is a private investigator originally engaged by Kanako Yamazaki to forcibly retrieve Arashi for the decaying mansion she shares with Yayoi. Sensing Kanako's unsettling aura and witnessing her harmful intentions towards Arashi, he shifts allegiances, aiding Hajime Yasaka during the mansion infiltration. His personal history is intrinsically linked to Arashi's past; he is the son of a man Arashi saved during a World War II air raid by preventing him from fishing that day. This rescue forges his connection to the series' supernatural events. Murata lost his right eye defending his family from yakuza attackers, though the specific circumstances remain undisclosed.

Following the resolution of the conflict with Kanako and Yayoi, he forms a supernatural bond with Kanako, becoming her primary source of vital energy. This link sustains her ethereal form and grants them joint time-travel abilities. Murata transitions into a supportive role, becoming a regular presence at the main characters' café. He assists with tasks, integrates into the group dynamic, and frequently appears alongside Kanako in group activities, such as accompanying her to check on Hajime during a rift with Arashi. He is consistently identified by his nickname "Gura-san," derived from his habit of wearing sunglasses ("sangurasu" in Japanese).