Light Novel Volume 6

The strongest dull prince's battle for the throne 6, The SS rank prince who acts incompetent will control the succession war from the shadows (最強出涸らし皇子の暗躍帝位争い 6　無能を演じるSSランク皇子は皇位継承戦を影から支配する lit. Saikyō degarashi ōji no an'yaku teii arasoi 6 munō o enjiru SS ranku ōji wa kōi keishō-sen o kage kara shihai suru ) is the sixth light novel of the series and was published on February 27, 2021.

Summary
The next secret maneuver showcases the talents of the dull prince!?

Finne is flooded by marriage applications from many young aristocrats. To break through the deadlock, Arnold makes full use of the power of the royal family, with the aristocrats unable to do anything. Also, Leonard's first love appears as a guest to the commemorative ceremony!?