After Carlos, an impoverished teen from a fractured home, receives a desperate note from Sarah, a pen pal he lost touch with a year ago, he uses her letters to solve the mystery of her disappearance and crimes she may have been a part of.
Root Letter, stylized as √Letter, is a 2016 visual novel adventure video game developed and published by Kadokawa Games for PlayStation 4, PlayStation Vita, Microsoft Windows, Android, and iOS. It is the first entry in the Kadokawa Game Mystery brand, and was followed by Root Film in 2020.