The Detective Boys reminisces of the Hatoyama Farm Case and talks about the new rabbit at their school. On the other hand, Haibara hears the words "Face, Black, Sherry" and starts thinking of the Black Organization with a frightened face. Conan tapped her shoulder and asks what's wrong, but Haibara replies "Nothing!".
At their school, the kids take care of the rabbits and Haibara suddenly sensed a stare. While Conan says to her not to worry about the recent case involving BO, a guy recognized Haibara as Shiho Miyano. The kids protect her, but it turns out they are alumni gathering for a reunion. The alumni tell Rumi that they are planning to dig up a time capsule buried before their graduation to liven up the reunion party. Shou Murata mentions they are waiting for Akemi Miyano since she was the one who buried the capsule. They are worried if she doesn't come, which Sumiko then shows a clue for the location, and the three are startled. Conan suggests he and the kids will help their search and tells Haibara he will secretly give the message to her after he finds it before the others.
After that, they split up into three groups. Conan's group goes to the principal office since the code starts with "Monet, can be shown" and the principal used to have a monet replica in his office. While searching, Conan asks Murata what kind of person was Akemi. Murata replies she was bright, kind, thoughtful, and popular. Haibara is happy after hearing that. Meanwhile, Mitsuhiko's group is searching in the infirmary. Mitsuhiko searches the hand-washing sink. He says to Ichihashi that the second line, "Doctor, don't tell a lie" is "Tell a lie" in English. (In Japanese, "Tell a lie" is pronounced as "Te arai", meaning hand-washing.) Ichihashi comments that Mitsuhiko is smart. Kobayashi then comments Ichihashi must be smart too since she's a doctor. The 3rd group, Genta, Rumi, and Yanagimachi is searching in the home economics room. Rumi says she thought the third line, "Don't burn" indicates of the room since it's where we use fire. Rumi and Genta mention an incident involving 1000 paper cranes for a chorus contest which made the music room almost burned.
The one who tried to sabotage the search for Akemi's time capsule is Gaku Yanagimachi. He wanted to keep people from finding the time capsule since he thought Akemi had hidden a confession about what Gaku and his two friends had done in elementary school. They were the ones who had caused the fire in the music room 14 years ago by accident and Akemi witnessed them. On the day of graduation, Akemi told Gaku to Be brave, which he misinterpreted as her wanting him to turn in. Years later, a few days before the class reunion, Yanagimachi went to Akemi's apartment so he could ask her to not tell anybody about it, but found that the apartment seemed to have not been occupied for a long time, although he didn't know she died. Thus, he sent invitation letters to the two others so he could use them as a cover to dig up the time capsule by himself and take out the possible incriminating evidence of his past crime.
It turns out that the time capsule was not in the equipment room, but in the breeding hut. The evidence is the fact that her name on the cipher was written vertically, and not horizontally, like the rest of the cipher, and since she used to be a member of the library committee, Conan deduced that her name represented her, and the cipher represented the computer keyboard of the library. All they had to do was input the four lines of cipher in hiragana on the keyboard to get the letters formed by each sentence on the keyboard. The letters formed were しいくごや (Shiikugoya), which meant the breeding hut (飼育小屋). After Yanagimachi confesses, Murata reveals he had copied a painting from Akemi and that his's got hung in the principal's office instead, and thought that Akemi might be angry about it and write about it inside her time capsule. Ichihashi also says she had cheated on Akemi because she looked at her copy in a Japanese examination. After they unearth the time capsule, they find a postcard from Akemi which says she wishes everyone's dreams to come true.
Yanagimachi also finds out the fire wasn't caused by him, but by the air conditioning being broken, and that Akemi's message to him was for him to stand up for himself and stop hanging out with bad people. Seiko remembers that after she cheated on Akemi and that both got scolded, Akemi offered her help to study, which helped her greatly in her grades. Murata finishes by saying that maybe she didn't enter the art competition because she wanted him to believe in himself more. The three of them then wish they could meet her again, not knowing what really happened to her.
Rumi watches Wakita leaving after he delivered the sushi. Wakita knows that Akemi was in the 19th graduating class, but muses to himself that a dead person would not be able to appear at their reunion.
