Saneatsu Mushanokōji appears as a male with striking red hair extending to his neck and matching red eyes. His identity draws directly from his historical role as a Taishō-period Japanese novelist, poet, and Shirakaba school philosopher, shaping his narrative portrayal as an idealist committed to humanistic values and enacting his principles.

Functioning as a supporting alchemist, he preserves and restores corrupted literary works. His key ability manipulates "strings of fate," enabling strategic control over events tied to people or objects. This power demands considerable physical and mental exertion despite its tactical advantages.

Personality-wise, he exhibits introverted, melancholic traits and profound literary devotion. Missions elicit a calm, stoic demeanor, complemented by analytical rigor—evident in his meticulous data gathering and alchemical experiments, reflecting systematic methodology.

His dynamic with fellow Shirakaba founder Shiga Naoya emphasizes their enduring collaborative bond, contrasting Saneatsu’s sheltered disposition against Shiga’s maturity while anchoring their shared ideals. Dedicated to averting dimensional collapse, he employs alchemy for textual analysis. Though reserved, his unique skills render him indispensable to the team’s objectives.