Synopsis

After his father is killed by the Demon King, a young man named Erius swears revenge. On the night he completes the skill acquisition ritual,

“Normally, defeating the Demon King would require ten years. But if you make a deal with me, a new skill can shorten that time to five years.”

He encounters a mysterious man who calls himself “Kuro” and proposes this bargain.

Though he senses something suspicious in Kuro's words, Erius accepts the deal in order to avenge his father as quickly as possible and to reduce the number of victims caused by the Demon King's army.

As a result of the deal, the skill he obtains is called

“Guide”

A skill that allows him to repeatedly relive his life from age fifteen to twenty, discovering what chains of causality are necessary to defeat the Demon King.

By using the power of Guide to repeat those five years again and again, Erius meets people with powerful skills, such as a Saint and a master spearman, and begins to feel confident that defeating the Demon King is truly within reach, but……

During one of these repetitions, Erius meets Nonoa, a girl who possesses the “Accounting” skill, considered a useless skill for adventurers.

And through Guide, he learns that it is his fate to first bring her into his party, and then expel her.

Torn between the guilt of casting her out and his sense of duty, Erius suffers deeply. Even so, time and time again, he expels her while saying,

“I don't need someone with a useless skill.”

At the same time, he continues to test and search for anything else he might be able to do.

And when his long struggle finally bears fruit, the curtain rises on the “true story”.

This is a story of people passing on their feelings, and slipping a “small hope” into the depths of despair.