One of the central themes and challenges of How a Realist Hero Rebuilt the Kingdom is the relationship of realism to isekai fantasy tropes. The stage of this conflict is the machinations of an aspiring civil servant named Kazuya Souma in the fantastical setting of Elfreiden. While Souma (as he is called) does not at all fit the mold of an isekai hero, it is his lucid appreciation of this fact in light of the more intangible circumstances of this expectation that ironically allow him to be a "realist" hero.
Throughout the series, Souma's attempts to solve the many issues facing Elfreiden problematize many cliches of the controversial isekai genre, particularly in the interaction of realistic versus fantastical elements. However, beyond his considerable intellect and pragmatism, what enables Souma to survive the first of his many tests in Elfreiden is a more subtle "realism" -- his ability to intuit the psychological and emotional "facts" that underpin decision-making and work them to his advantage. Souma's uncanny gift is identified by Princess Liscia, who upon learning about Souma's summoning to Elfreiden -- and the special circumstances surrounding her family's rapid, bloodless overthrow -- smartly remarks, "You really are a huge realist, huh?"
Reading The Room
While Liscia's remark sets up the series' titular theme, it begs the question of what powers a "realist" hero possesses. The details of Souma's unexpected summoning to Elfreiden in part answer this question, in a way that draws attention away from Souma's skills at statecraft and policy and more toward his understanding of how psychology affects decision-making, as well as his empathetic capacity.
Souma doesn't waste time trying to deny either the reality of what's brought him to Elfreiden or argue against its unfairness. Instead, the focus of his interactions with King Albert and his ministers is to probe the extent of Elfreiden's extreme disarray, seeking a way to profit from the kingdom's palpable helplessness.
Instead of resisting Elfreiden's unreasonable demands for a generic isekai hero to fight generic Demon Lords -- a function he knows he cannot fulfill -- Souma offers Elfreiden what it really wants: lasting solutions to the mundane problems that have led to this point of desperation, and which the kingdom is now scrambling to provide through fantastical, cliched means. To Elfreiden's unreasonable, unrealistic and "generic" demands, Souma counteroffers with a promise of specific solutions to their more pressing, real problems. Shocked to be offered far in excess of what they have just asked for, the King and his ministers immediately accept.
A Different Kind of Hero
This interaction illustrates Souma's "realism" and Liscia's ironical remark into focus. Beyond understanding the undeniable weakness of his position as an unwilling abductee in a fantastical world, again, it is Souma's ability to rapidly appreciate the emotional and psychological "facts" of a given situation and turn these elements to his advantage. Notably, at the time Elfreiden accepts Souma as its Chosen Savior, he offers nothing in the way of concrete solutions. Instead, his tone and demeanor provide what he has ascertained the Elfrieden court needs most: confidence.
Although Souma's skills and knowledge eventually prove to be substantial, in this critical moment, it is Souma's ability to discern the psychological and emotional "reality" of Elfreiden's desperation, and immediately beginning working this "fact" to their mutual advantage, that illustrates the true power of a "realist" hero.
To this end, Liscia's interest stems from her special position in the story. While intimately aware of Elfreiden's desperation and helplessness, the final piece arrives only after she belatedly confronts Souma. However, the confrontation goes much differently than she expects: upon learning exactly how Souma has swindled her family out of their kingdom through their own incompetence and desperation, Liscia is stunned to realize that the usurper is uninterested in the throne, yet still determined to rescue the kingdom from the very qualities that brought him the throne in the first place.
