This protagonist, Kara, had reasons for not leaving the Royal City. He considered himself special among all protagonists because his system allowed him to make a choice every 24 hours.
Making good choices would grant him various abilities. However, these abilities only lasted for 24 hours, after which they would disappear.
"Gaining Strength by Touching Corpses" was an ability Kara obtained from one of these choices.
Previously, the system presented him with choices, one of which resulted in the ability "HP Lock."
Additionally, his system had a feature that allowed the duration of his current ability to be extended by 24 hours for every antagonist he killed.
In simple terms, each antagonist he killed prolonged the effectiveness of his current power.
Thus, he persevered, battling demons and even fortuitously eliminating an antagonist. His strength quickly evolved from elite-tier to 1-star general-tier.
