"Red Thread") is a Japanese horror adventure game by Success Corporation, released exclusively for the PlayStation 2 in Japan on October 21, 2004.

A reduced price "popular edition", included in developer and publisher SUCCESS' SuperLite 2000 Series, was released on October 27, 2005.

A remastered "HD" version for the Nintendo Switch and PC, along with its younger "sister-game" Aoi Shiro, was released on May 24, 2023.

[2] After the death of her mother, orphaned high school student Kei Hatō heads for her late father's house in Hemizuka to settle issues with her inheritance.

The main character of the story, Kei is a rather careless person, which is quite ironic considering her favorite phrase is "always be prepared".