After Conan's investigation, he realised that the attacks happened February 22nd, not February 15th. Like that, he connects all the information and tranquilises Kogoro in the hospital. With both Kataoka and Yoshinari reunited, he says that the one who sent the threatening letters to Masamura was none other than Hiroki Kataoka, as the printer stained both the threatening letters and Kataoka's fliers, meaning that the is the one who sent them. He admits that he was against Masamura publishing a novel of attacking men, as it might generate a bad influence on youth, even though he, along with Yoshinari and Yasuki were part of the attacks of February 22nd, 20 years ago, meaning that Masamura wasn't really involved. Kataoka admist that he didn't kill Masamura, as he was in Haido Hotel at the time. Yoshinari also had an alibi. So, who did the murders?
The Real Culprit
It turns out there was someone hearing behind the door of the hospital room: Takeuchi, the nurse that said that Kogoro is similar to her deceased father.
THe shocking truth is that Chigusa Takeuchi, as her given name is Chigusa, was the daughter of Yuji Takeuchi, the man who was attacked by the three men. She is the one who killed Masamura. That day, Mr. Takeuchi was supposed to give a stuffed shark as a present for her daughter, but in his way back home he was attacked. She confesses that she only wanted to know what happened to his father. It was their fault Chigusa's family fell apart, as her father lived in hospital for the rest of his life before dying, and her mom remained frail for experiencing fatigue. Chigusa says that Masamura pressured her to give her statement, and that how it feels to be a victim. Feeling scared of being attackes just like her father, she sprayed pepper gas and beated him with the baseball bat. Chigusa cries in repent how she did the same thing Kataoka and his friends had done to her father. Yoshinari shows regretful, but Kataoka doesn't, meaning that he doesn't care at all about the attacks. Megure says that Kataoka will probably receive a visit from investigators to investigate about the threatening letters.
Yuji Takeuchi
Deceased
Chigusa's father
Attack victim
Aftermath
After being released from the hospital, Kogoro encounters some admirers, ad obviously he went with them. Conan exclaims how he thought Kogoro was supposed to work.
Trivia
In one of the magazines that Masamura serialises his novel, Kaori Shinmei's name appeared on the front cover.
An interview with her is probably published in the magazine, regarding her work "The Murderer From Hell" (黄泉からの殺人者).