Root Letter (stylized √Letter) is a visual novel adventure video game that is developed and published by Kadokawa Games as the first title in their Kadokawa Game Mystery brand. In the game, the player must figure out what happened to the character of Aya,
“我杀了人。犯下的罪必须偿还。
必须就此告别了。再见。”
这是一款为了确认高中时的笔友文野亚弥在最后一封信中所写内容的真相,必须凭藉着当年与她来往的十封信,探索有着美丽的自然与历史人文背景的岛根县境内城市,设法查明谜团真相的推理冒险游戏。
玩家将得在反覆进行回想十五年前信件内容的“信件部分”、寻访岛根各地找出知道真相的“七位同学”的“探索部分”,以及在找出同学后与其当面对质问出真相的“追问部分”,借此一点一滴追查出这位笔友的真相。