Isekai Tantei Reijou ~Oshi no Shi no Shinsou o Abakasete Itadakimasu~

The protagonist detective, Hana Kuroda, for some reason finds herself lost in the world of her beloved historical mystery novel. While helping an injured nobleman, Gabriel, on the roadside, she discovers that Gabriel is the younger brother of her most cherished character! As a thank you, she is invited to the duke's mansion. She thinks, 'Finally, I can meet my favorite character!' only to find that he has already died under mysterious circumstances. Not only her favorite character, but even Gabriel, his younger brother, is surrounded by scandalous rumors in the duke's household. On the condition that she can live in the duke's mansion, Hana investigates the incidents that could shake the duke's household and the country, while searching for a way to return to her own world. — Credits: Original work by Eri Hauo, name by Romi Kotaki, character line art by Shino Sasaki. Original Webtoon https://ebookjapan.yahoo.co.jp/stories/145929/