[Crossover] Has the Heroine Crashed and Burned Today?

Everyone at the detective agency knew that Kunikida had a lover who had died long ago. She was the only romantic indiscretion of a man who made everything rigidly idealistic, and the one painful exception to the plans he tried to make so calmly for everything. Everyone at the agency knew this, so none of them ever brought it up in front of him. Until one day, facing the only honest person still in the dark, they couldn't hold back any longer: "Kunikida, your girlfriend came back from the dead, and that black-mud freak Dazai is all over her!" "Akutagawa Ryunosuke from the Port Mafia even brought over a marriage application!" "That gravity user went to get custom wedding rings made yesterday!" "Today, someone even brought their whole family to see your girlfriend, saying the kid can't grow up without a mother!" "That information broker next door has already moved his base of operations here!" "And... Hey, wait, President! Why do you look so upset?" Kunikida: For fuck's sake. What to expect before diving in: * A deadly love rivalry * Gender-swapped canon female characters * An extremely beloved heroine and a love rivalry * The heroine collects tragic endings like souvenirs * This story is a bundle of out-of-character behavior, melodrama, and wish fulfillment * There is nothing I won't make dreamy if you can imagine it * Chaotic plot, a ton of headcanons * Everyone is a hopeless romantic * Please don't spam the comments with BL ships * Ranpo doesn't have a script in this story. Without sufficient evidence or deliberate prompting, he can make mistakes in his deductions. * The schemes may not be all that devious. Tentative worlds: Bungo Stray Dogs, Durarara!!, Touken Ranbu, Ouran High School Host Club, The Lover of the Emperor, Kuroko's Basketball Theme: