The setting of the story is not directly connected to any other Fate work. Kanata Akagi is a boy from a declining magus family who decided not to pursue magecraft and live a normal life instead. His friend gives him a light novel that claims an explosion that devastated the Imperial Capital of Tokyo 75 years ago was caused by a battle between supernatural beings. While going through his late grandmother's belongs, he accidentally activates an hourglass that sends him 75 years into the past. While seeing characters and events that reflect the light novel, he has no idea what a Holy Grail War or Servants are and is out of his depth when he accidentally summons Saber.
- Kanata Akagi - Master of Saber. A teen from AD 2020 (Reiwa 2) who was sent back in time.
- Tsukumo Fujimiya - Attempted to summon Saber, but the process was interrupted by Kanata. Holy Church representative Master of Saber in the original timeline.
- Saber - Okita Souji, Servant of Kanata Akagi.
- Master of Archer
- Archer - Oda Nobunaga
- Major Magatsu - Male Imperial Japanese Army Master of Berserker
- Berserker - Mori Nagayoshi
- Master of Caster
- Caster - Maxwell's Demon
- Master of Assassin - A female German Third Reich Master of Assassin.
- Assassin - Okada Izou
- Mysterious Officer - A male German Third Reich Master of the Gert Krieger Lancer
- Lancer - Held Krieger Servant killed by Saber directly after her summoning.
- Mr. Fujimiya - Kanata Akagi's father and son of Tsukumo Fujimiya.
- Toyotomi Hideyoshi - Cameo appearance fighting Nagao Kagetora.
- Nagao Kagetora - Cameo appearance fighting Toyotomi Hideyoshi.