※Currently serializing as a manga on Hakusensha Manga Park. ※Also published on Kakuyomu. The Kakuyomu version incorporates some additional episodes into the main story, changes the heroine's name to match the manga, and adds more episodes. Strongly recommended for those coming from the manga version. After his father is killed by the Demon King, the young man Elyus swears revenge. On the night he completes the ritual to acquire a skill, he meets a mysterious man named 'Kuro' who offers to reduce the ten-year period required to defeat the Demon King to five years in exchange for a deal. Despite his suspicions, Elyus accepts the deal to avenge his father sooner and reduce the number of victims caused by the Demon King's army. The skill he acquires, 'Guidance,' allows him to relive his life from age fifteen to twenty multiple times, discovering the necessary causes and effects to defeat the Demon King. As he repeats the five-year cycle, he meets powerful skill holders like the Holy Maiden and the Spear Master, feeling a growing sense of accomplishment in his quest to defeat the Demon King. However, during one of his repetitions, he meets Elaine, who has the 'Accounting' skill, considered a useless skill for adventurers. Through 'Guidance,' he learns that he must banish her from his party. Elaine, after being banished, awakens to the strongest skill, 'Master of Numbers,' and begins to excel. Meanwhile, Elyus is belittled by others as an incompetent with poor judgment and falls from grace. Despite this, he continues to repeat his life, searching for the necessary causes and effects to defeat the Demon King, torn between his guilt and sense of duty in banishing her. He repeatedly tells himself that 'useless skill holders are not needed,' while continuously testing if there is anything else he can do for her, believing that one day she will defeat the Demon King. This high-fantasy work, newly submitted in 2021, ranked first (9.7/10.0) in reader satisfaction among the top 100 works in terms of overall evaluation points. ※Main story completed ※Additional episodes available ※This is the complete edition of the same main title, with added episodes and a new ending. The subtitle has been changed.