Inference: Rukawa Kaede:
(1) I didn't kill Xiandao. I have never been to Dawson's house this year.
0? I don't hate cherry trees. If Akagi says I'm the murderer, it's a lie.
According to "three answers are right and the other answer is wrong"
A is telling the truth, so Rukawa Kaede is not the murderer.
And then what? 0? I don't hate Sakuragi. It's a lie
Akagi Takenori:
I was at home when Sendao was killed. (b) I have never killed anyone.
0? Rukawa Kaede is the murderer. (d) Mitsui and I are good friends.
From the above analysis, C is a lie. According to "three answers are true, the other answer is false", and B is true, so Akagi Takenori is not the murderer.
I was at home when Sendo was killed. It's the truth.
Mitsui Hisashi:
(1) I didn't kill Xiandao. Rukawa Kaede has never been to Xiandao this year. ? 0? I'm not familiar with Akagi. In the afternoon, I was practicing with Sakuragi.
Because Akagi Takenori: (d) Mitsui and I are good friends. It's the truth.
So Mitsui Hisashi:? 0? I'm not familiar with Akagi. This is a lie.
According to "three answers are true and the other answer is false", (1) I didn't kill Dawson, which is true, so Mitsui Hisashi is not the murderer.
(d) That afternoon, I was practicing with Sakuragi. It's the truth.
Miyagi Ryota:
(a) If Sakuragi says that he has never owned a pistol, it is a lie. (b) Dawson was killed on the eve of the final.
0? Akagi was at home when the murder happened. One of us is the murderer.
B D is the truth, such as the title.
According to Akagi, C also holds, so
If Sakuragi says that he has never owned a pistol, it is a lie.
Hanamichi Sakuragi:
(1) I didn't kill Xiandao. I've never owned a pistol.
0? Rukawa Kaede hates me. I was practicing that afternoon.
D is the truth, because when I practiced with Sakuragi that afternoon, Mitsui's (D) was the truth.
Is the truth because of Rukawa Kaede? 0? I don't hate Sakuragi. It's a lie
B It's true, and (b) I've never owned a pistol.
According to Miyagi Ryota, A is a lie. (a) If Sakuragi says that he has never owned a pistol, it is a lie.
So it's a lie that I didn't kill Dawson. Hanamichi Sakuragi is the real murderer.