Kandou Sareta no de Tanteiya Hajimemasu! Jitsu wa Boukoku no Joou da Nante Naisho Desu

Octavia de Reine is stripped of her noble status when her illegitimacy is revealed. Initially unfazed, she soon faces opposition from her father and former suitor, who seek control of the family estate filled with enigmatic heirlooms left by her grandmother. Unaware of the larger legacy she is meant to inherit, Octavia aims to follow her grandmother’s path as a renowned detective. She must contend with rival nobles, shadowy thieves, and enchanted artifacts tainted by demonic influences. A vengeful angel queen also poses a threat. Adding to the intrigue is a young marquis who appears overly interested in her.