Hartknights Lapis-Lazuli Lacmouth holds the title of Crown Prince in the Lapis Lazuli Kingdom and was originally betrothed to Tiararose Lapis Clementille as part of an otome game's storyline. Within that narrative framework, he adheres to scripted events culminating in Tiararose's public condemnation and disengagement at an academy graduation ceremony—an act typically leading to her exile. This judgment scene defines his core narrative purpose in the main story.

Completing the first volume of the visual novel adaptation unlocks a bonus segment offering alternate context. It reinterprets events from the original "Ring of Lapis Lazuli" game, depicting comparatively kinder treatment of Tiararose by Hartknights during their engagement. No canonical expansions beyond this engagement narrative and condemnation scene exist across documented media adaptations.