A time slip 4.8 million years into the past leads to the Tokoyo civilization. An SF fantasy begins!
About
Introduction
Synopsis
Due to a mistake in operating a time machine, Guest and the others were thrown 4.8 million years into the past.
In the process, a single research notebook and a picture book called "Princess Kaguya" were dropped, triggering a butterfly effect that gave birth to the advanced civilization "Tokoyo," which does not exist in the true history.
If history is not corrected within 72 hours, the ripples will reach the modern era, and not just Guest, but human history itself will vanish.
Future humans living in the true history and the newly born Tokoyo civilization cannot coexist.
However, the people of Tokoyo had known this fate for two thousand five hundred years.
The final hope they entrusted to the future— that is the "World-Line Branching Project."
The final piece to complete the plan is the time machine coming from the future.
By docking the time machine with the World-Line Branching Craft, which carries the core to enable branching within 72 hours, a new world-line must be born.
However, that plan came with an unavoidable price.
One person cannot return.
SF Knowledge Manga
Characters
🧪 Koichiro Amaki Guest's older brother
Age: 28 Role: Scientist / Time Machine Developer Personality: Logical, calm, strong sense of responsibility Likes: Family, coffee, research
Overview: The genius scientist who developed the world's first time machine. He cherishes his daughter, Kaguya. Though he suffers knowing his research notes started the Tokoyo civilization, he continues to search for a way to save both the civilization and the modern era.
🏹 Mitsuru Shirotani Guest's childhood friend
Age: 17 Role: Archery Club Member Personality: Sincere, calm, polite Likes: Archery, training
Overview: The only young man carrying no specific mission. Because of that, he values life more than anyone. He supports his companions using the "strength of an undisturbed heart" cultivated through archery. He keeps searching for a path where everyone can return smiling.
👑 Kageaki
Age: 52 Role: Great King of Tokoyo Personality: Gentle, wise, tolerant Likes: Talking with the people, family, peace
Overview The king who rules the 2,500-year-old Tokoyo civilization. A wise ruler deeply loved by his people, he warmly welcomes the future humans who arrived on "The Final Day." A statesman with a great heart who seeks to save the lives of future humanity as well as his own civilization.
🎋 Tsuguto
Age: 26 Role: First Prince / Branching Project Executor Personality: Calm, sincere, strong sense of responsibility Likes: Family, training, the citizens
Overview The first prince of the Tokoyo civilization. A young man who personally chose to be the executor in the branching device core room to connect the civilization to the future. While he accepts his mission, meeting Guest and the others makes him realize his true wish: "I want to live."
🌙 Kaguya
Age: 18 Role: First Princess Personality: Kind, intelligent, deeply compassionate Likes: Flowers, picture books, children
Overview The first princess of the Tokoyo civilization. She is dearly loved by the people as the princess who inherits the name "Kaguya." She treats everyone equally and warmly welcomes the visitors from the future. Knowing the fate of her brother, Tsuguto, she continues to wish for a future where she gives up on neither the civilization nor her family.
⚙️ Akatsuki
Age: 34 Role: Top Scientist of Tokoyo Specialty: Time Theory, World-Line Branching Theory, Branching Device
Overview The genius scientist who brought 2,500 years of Genesis research to completion. He put the world-line branching device into practical use and had been waiting for the arrival of the future humans. He respects Koichiro not as a legend, but as a fellow scientist, and pursues the best way to save both the civilization and modern humanity.
⚔️ Kogi
Age: 50 Role: Commander-in-Chief of Tokoyo Military Duty: Overall Command of Execution Team / Royal Guard
Overview A loyal retainer serving two generations, Kageaki and Tsuguto. A soldier who protects the country more strongly than anyone despite hating war. He insists until the end that "I, not the King, should be the executor" for the branching project. His loyalty is heavier than his life.
📖 Fumihiko
Age: 16 Role: Royal Library Chronicler Duty: History, Tale of Tokoyo, Civilization Records
Overview A young chronicler who leaves the history of Tokoyo for the future. He has a great thirst for knowledge and a strong admiration for people from the future. He accompanies the team as the final chronicler for the branching project, the person who will write the final passage of the Tale of Tokoyo, spanning 2,500 years of history.
Sourcebook
Intro
One day in the year 206X, in the basement of the Amaki residence— Guest was showing childhood friend Mitsuru the time machine invented by older brother Koichiro.
Ko-nii's time machine is finally finished!
When Guest removes the blue tarp, a large sphere reveals itself. The interior is cramped but designed to seat four.
He said you enter the time you want to jump to here. For example, if it's 2 days ago, you put in 48... he said.
Guest tentatively touches the control panel and inputs "48" into the coordinates.
And then, this lever in the back...
CLANG
Creator Comment
Release Date 2026.10.05 / Last Updated 2026.10.05
