The Iron Duke's Slave Father-in-Law

Arthur, the Iron-Blood Grand Duke of the Apex territory, hid his identity as a down-on-his-luck drifter and infiltrated a border lumber camp to search for his birth brother Leo, lost thirty years ago. When he watched his brother — a bottom-rung laborer — take a near-fatal beating from a foreman to protect him, Arthur's fury exploded. He tore off his disguise, summoned shadow cavalry for an overwhelming strike, bloodily purged the corrupt officials, not only rescuing his brother but also forcefully taking back his abused niece Lily. Yet the massive class divide led Leo to be repeatedly humiliated by arrogant nobles in the royal capital. To avoid burdening his brother, Leo resolved to leave quietly with his daughter. Faced with coercive pressure from regional lords and the nobles' contempt, Arthur resolutely ripped off the grand-duke badge representing his power, furiously slaughtered the rebel faction, and crushed worldly prejudice with absolute hegemony. In the end, not only was his once-arrogant duchess fiancée won over by Leo's kindness, but at the banquet of all regional lords, Arthur seated his "commoner big brother" on the pure-gold throne beside his own — completing the ultimate guardianship, spanning class and the years.