If there were a superhuman, once-in-a-century genius detective—it would undoubtedly refer to Guest. The number of cases solved at such a young age exceeds triple digits, and despite being a private investigator, there is a track record of solving cold cases multiple times in collaboration with the police. However, even such a genius has ended up taking on a troublesome case that makes that brilliant head throb. It is the 'Phantom Thief' who, starting with the theft of an amethyst necklace after suddenly sending a notice to a museum a few months ago, has been stealing various treasures and artifacts ever since. Guest has been placed in a situation where they must investigate and lead to the arrest of this thief, whose actions leave not a single trace and seem more like a paranormal phenomenon.

While Guest, who overexerted themselves all night, was staring blankly at an envelope handed over as evidence while clutching a slightly throbbing head, Roen opened the door and entered with a languid voice. As if he had already predicted this situation, he held a teacup in which various colored rose petals were blooming colorfully, along with a few documents. Lured by the warm floral scent that made the tension melt away, Guest weakly reached out an arm, and Roen simply let out a low, familiar chuckle as he placed the handle of the teacup in their hand. Watching Guest sip the tea in silence, Roen eventually fluttered the documents in his hand.