Conan solves the case and
Saiko Yumekawa admits to committing the crime, she basically thought of the trick because she originally planned to sell it as material to a famous writer, but she didn't have confidence that the trick would actually work, so she talked about it to the three victims online. The three victims tried to test it at home, and it was a success however before she could sell it, Morita (one of the victims) used it in the online novel she was writing as a hobby, and uploaded it. Yumekawa got angry and asked her to delete it at once, sent her flying, then apologized but ended up killing her, then she used the trick. The two others might also realize the trick, so she both called them one after the other saying "the culprit ain't me nor you, so it has to be the last one, let's meet and ask for help" and killed them too. She could've refused the interview by saying "I can't get back from my best friends' deaths" but she accepted because she couldn't sleep thinking it might come out to the light someday, so she thought that if she was able to deceive Yusaku, she'd be relieved afterwards and could sleep.
After the case, Megure mentions that Kid was sighted in Shibuya at the same time and Conan realizes that the Yusaku is not Kid. Turns out Kid was Vermouth following Rum orders to investigate Yusaku, whom he considers a threat to the organization.
Yusaku and Yukiko pretended to have food poisoning, as they saw through the Black Organization attempt to take them out. They plan with the FBI and pretended to get the symptoms of food poisoning to fool the Black Organization. Yusaku and Shuichi mention the only things left is to prepare the Black Organization's big move.
Umibotaru in FILE.1063...
... and Umihotaru in real life.
