"So, what should I do next?" Haibara Ai bit the straw and asked casually.

"That's all right. The four of them are probably playing mahjong somewhere on Saturday night. Just investigate the family or company addresses of these four people twenty years ago, find out the mahjong halls they might go to, and then go to inquire one by one."

Conan smiled and said confidently: "Even if you are just strangers when you go to the mahjong hall, you can ignore the age gap and get together to play mahjong, right?"

"It makes sense." Takagi Shuo nodded frequently.

Yuan Taisan drank all the drinks in just a few sips and was already by the car and ready to set off.

"It's already so late, it doesn't matter if you don't go home?" Chen Xing asked.

"You don't have to worry."

"We've told our parents."

"Tonight, you can do electric power at Dr. Agasa's house!"

Although their excuses are the same, they are really hard to refute.

"Then let's go!" Takagi was full of motivation.

Chen Xing looked at Conan again and found that the boy's eyes were bright and impatient.

"It seems you need to be motivated too." When getting in the car, Ai Haibara chuckled.

"Okay." Chen Xing made a cheerful gesture to her.

"Old-handsome." Haibara Ai curled his lips and got in the car.

"..." Chen Xing.

...

"I still remember these people. They were all guests who often played mahjong here a long time ago. I liked them very much."

The owner of the mahjong hall looked at the photo in front of him and sighed with emotion: "It's really nostalgic."

"What about this person?" Takagi Shuo handed over the photo of Hirato Doji.

"I don't know him, who is he?"

"He is a criminal psychologist, Mr. Doji Hiroto, and only this person's photo is the closest," Takagi explained.

"Ah, I remembered that he is a student who often plays cards with those three people." said the owner of the mahjong hall.

"So these four people have played mahjong here before?" asked Takagi.

"Well, every Saturday night, four people are all here at one to ten o'clock." The boss recalled: "A doctor, a teaching assistant in the science and engineering department, a lawyer who has just debuted and a college student studying criminal psychology."

He smiled and said, "Although they are different in age, they seem to be very good at it. When playing mahjong, they always reason about cases that occur in reality. For example, the murderer is the husband who appears during an interview, and the criminal method uses medical knowledge. And they say it almost every time, which is surprising."

After talking about it, the boss then wondered: "By the way, what happened to these four people?"

"The four of them were all killed." Takagi Sugh said in a deep voice: "All of them were killed by the same murderer..."

"What did you say? Kill four people in one breath?!" The boss couldn't help but exclaim.

In the small store, the originally slightly noisy environment suddenly became quiet, and those who were touching and playing cards subconsciously looked over.

Takagi Suk quickly whispered: "No, the first murder happened twenty years ago, don't you know?"

"Because I rarely read the news, at most I only read the cases that the four people had reasoned in the newspapers." The boss said: "However, there were only these four people playing cards here for the two years. After they didn't come, I didn't even buy the newspaper."

"Do you know why they are not here?" Takagi asked.

"I didn't hear that clearly that time, and after that, the student would come over to see it, just sitting alone at the mahjong table, wiping the mahjong plaque a little lonely." The boss said, "Wait, maybe the murderer was even that man."

"That man?" Takagi Suk said hurriedly.

"I still remember a guest who always provoked the reasoning of the four of them. Then when the four people stopped getting together and the student was waiting alone, the guest looked at the right time to make fun of the student, but the two fought." The boss said: "At that time, the guest shouted like this: I must kill all of you!"

Takagi Shigeru looked moved, "Do you know who that person is?"

"I don't know, I only heard that he seemed to have done a lot of bad things, but I don't know what he called it." The boss said, and suddenly thought of something, "By the way, there was a case of a gun loss a long time ago. Someone took away his gun while the patrol officer was asleep, causing a big commotion. However, two days later, the gun was sent back. At that time, everyone was talking about whether it was this guest who did it."

"That's it." Takagi wades into his chin, and has no idea for a moment.

"And this, this is the card that was thrown out during that fight." The boss took out a mahjong box from under the counter and opened it. "Because this card was broken, it could no longer be taken out and used."

Conan suddenly said, "Is the person who threw this mahjong placard the guest?"

"Yes."

"Who packed this deck of cards?"

"We immediately called the police to deal with it. After the police took them away, I picked up the mahjong plaque and put it in the box."

"Then there should be only you, uncle, Mr. Pingdong and the fingerprints left by that guest, right?" Conan asked.

The boss was stunned for a moment, then looked at Takagi Suk, "Who is this little brother?"

"Ah, he is doing the social subject training." Takagi said with his head scratching.

Chen Xing thought for a while, "Since you are taken away by the police, you may have a record."

"Yes." Takagi beat the palm of his hand and put on gloves. "So, can you borrow these scratched cards first? You also need to take your fingerprints."

"Okay." The boss nodded, "At the time, I received a strange call last week asking if the person who played cards here twenty years ago was a doctor, assistant professor, lawyer, and criminal psychologist."

Having said that, when Conan asked again, he didn't get any valuable clues.

"Anyway, let's go to the police station to take a look now." Takagi Suk said.

...

"There is no fixed residence, no job, and the name is Guibao Dulang."

In the police station, Takagi Suk quickly found the record at that time, and after notifying Officer Meguri of the discovery, he also obtained information about the person.

Guibao Dulang is a robber murderer. He only ended his fifteen-year sentence a few days ago and was just released from prison.

"So the 15-year serial murder case was interrupted because he was locked in prison, so he could not kill people?" Takagi speculated.

"It's possible." Conan nodded silently.

"Okay, since the murderer is almost certain, please send you back first, right?" Takagi Sug said with a smile.

"I don't want it." Azumi pursed her mouth.

"We just found the murderer for you!" Yuan Tai said dissatisfied.

"Can you kill the donkey with your mill?" Mitsuhiko was angry.

"I don't mean that." Takagi Shirou smiled and looked at Chen Xing with help.

"Let's wait until it's completely confirmed." Chen Xing said.

"What?" Takagi Shiro was stunned.
Chapter completed!