Detective Conan File 1159 Spoilers: The Layered Cup Trick | Case Closed

“What happens in Detective Conan File 1159?”

“What are the spoilers and theories for Sunday Conan File 1159?”

The Tokyo planetarium case that began in File 1157 reaches its solution here.

This time, the series moves into its answer chapter. Below is a spoiler-filled look at File 1159, “It Is Still Okay…”

Spoiler warning: this article discusses the culprit, motive, trick, and ending of Detective Conan File 1159, “It Is Still Okay…”

From here on, I will cover spoilers, deductions, and impressions for Detective Conan File 1159, “It Is Still Okay…”, published in Weekly Shonen Sunday issue 13 released on February 24, 2026.

About the Latest Detective Conan File

For readers following the manga in Sunday, this is part of the same ongoing File-by-File coverage. File 1159 is the solution chapter for the planetarium case, so it works best after reading File 1157, “Under the Starry Sky…”, and File 1158, “The Eerie Sound.”

Spoilers for Conan File 1159, “It Is Still Okay…”

File 1159 resolves the planetarium case that continued from File 1157 and File 1158.

The setting is the music video shoot for the popular band Kyara Kyara. The band has four members.

• Vocalist Hatsune Sukuri
• Drummer Mitsuo Sakaki
• Bassist Hotaru Domura
• Guitarist Tosuke Akashi

Three hours have passed since Hatsune suffered from poison and was rushed to the hospital, and Conan and Heiji already seem to have a suspect in mind.

Heiji Begins His Deduction Show

Heiji first organizes what the other three members handed to Hatsune.

Sakaki gave her iced tea.
Akashi gave her popcorn.
Domura gave her fan goods bought at the shop.

At first glance, injecting poison into the popcorn looks like the easiest route. But that would not neatly explain why poison was found somewhere besides the popcorn, such as on the cup and her hand. The forensics results still left that oddity behind.

What Heiji focuses on is where the poison was detected: Hatsune’s hand, the popcorn container, and the iced tea cup.

A cup covered in condensation can be touched without seeming suspicious. If the poison was transferred through the cup, then Sakaki, the person in charge of the drink, had the easiest path.

With that line of reasoning, Heiji cuts Akashi off as the main suspect and starts cornering Sakaki instead.

What Was the Trick Used to Poison Hatsune?

Heiji’s reconstruction goes like this.

At first, Sakaki gives Hatsune oolong tea rather than iced tea.
Hatsune is the type who does not eat or drink during a screening, so she does not immediately keep drinking. After taking just one sip, however, she realizes it is oolong tea and silently trades cups with Sakaki’s iced tea.

That exchange is the key point.
The poisoned cup was the one Hatsune had first touched with her mouth: the oolong tea cup. By switching cups, Sakaki is able to retrieve the poisoned cup himself.

After that, Hatsune starts eating popcorn, the poison takes effect, and she collapses.

The poison on her hand, the reaction from the popcorn container, and the reaction from the iced tea cup all connect under this sequence.

The “Layering” Hint Was the Cup’s Double Structure

The decisive clue in the case was the strange-looking cup.
Near Sakaki’s seat, there was something that seemed to be two cups stacked together, and lipstick was also found on the end of a straw.

That lipstick came from Hatsune’s first sip. There were signs that Hatsune, bothered by the lipstick mark, had turned the straw upside down, and that tiny detail supports the fact that a cup exchange really happened.

Then comes the stacked-cup trick.

Sakaki first buys one drink, finishes it, and creates an empty cup.
He coats the inside of that empty cup with poison and stacks it with another cup to create a poisoned cup. From the outside it looks ordinary, but it can transfer poison only to the hand of the person who touches it.

After the incident, Sakaki also tries to swap his own cup with Heiji’s cup and act as if nothing happened.
The “layering” that made Heiji and Conan react at the end of File 1158 was pointing to these layered cups.

The Motive Comes from a Wanted Criminal’s Past

Sakaki’s motive was tied to the music video Hatsune had made.

In the student-era footage used in the video, Sakaki’s face looked almost like a different person. But that face matched Muneya Hario, the wanted leader of a serial arson group Heiji knew about.

In other words, Sakaki was likely hiding after changing his appearance.

Sakaki explains that he had been part of a delinquent group but wanted to leave, and that before he knew it, he was being treated as the leader.

His claim is that if the footage spread, it would cause trouble for his old associates and the people around him. That is why he says he did not use a lethal dose: he only wanted to create a disturbance with a light poisoning and stop the music video’s release.

Hatsune Had Noticed the Culprit: The Truth Behind the Dying Message

Just before collapsing, Hatsune internally reacts as if saying, “Hey, hey, hey! No way, so that is how you are doing it!” (unofficial translation)

That reaction suggests she had already noticed Sakaki’s setup at that point.

Then came the snapping sound. It was the sound of her tearing paper matches to leave a message.

The band name Kyara Kyara comes from kyara, a word connected to incense.

In the world of incense, there is also a pattern system known as Genji-ko, and one of its names and designs corresponds to Sakaki. The shape Hatsune made with the matches pointed to that Sakaki design, meaning she identified Sakaki through shape rather than text.

What Hatsune Meant by “It Is Okay…”

The “It is okay…” Hatsune says while collapsing is not about her own condition; it is meant for Sakaki.

The nuance is that he can still turn back, that it is still okay if he turns himself in and comes back.

Afterward, a call comes from the hospital confirming that Hatsune’s life is not in danger.

The music video also contains older visuals of each member that differ from how they look now, leaving a final aftertaste to the case.

What Heiji and Kazuha Wanted to Say

After the case, Kazuha tells Ran that she and Heiji are actually dating. Ran answers casually that she already knows because Conan was there at the time.

Heiji likewise tells Conan that he and Kazuha are dating. Conan cuts him off just as directly, saying he knows because he was there too.

So the “big talk” and “important talk” the two had been hesitating over were simply a report that they had started dating.

Momiji Ooka sees this and, while clearly frustrated, recites a waka poem in the mood of, “If I live long enough, perhaps I will look back fondly on even this painful time” (unofficial translation).

Quietly, she still burns with the thought that someday she will win Heiji over.

Characters in Conan File 1159, “It Is Still Okay…”

The main recurring characters in File 1159, “It Is Still Okay…”, include Conan Edogawa, Heiji Hattori, Kazuha Toyama, Ran Mori, Momiji Ooka, and Muga Iori. The case also centers on the band Kyara Kyara and its members Hatsune Sukuri, Mitsuo Sakaki, Hotaru Domura, and Tosuke Akashi.

Impressions and Theories for Conan File 1159, “It Is Still Okay…”

File 1159 was the final answer chapter of the three-part planetarium case.

Along with the solution to the case, it also pays off the Heiji and Kazuha romance thread, so the chapter ends up feeling fairly dense.
Here are the points that stood out most.

Impression and Theory 1: The Case Trick Was Easier to Follow Than Expected

This case was relatively easy to take in compared with some other multi-part cases.

File 1158 had already shown the odd feeling that a cup looked stacked, and once the incense-related word kyara appeared, the direction of the trick became easier to see.

The way the dying message connected to the Genji-ko design was also clean, and the idea of pointing through shape felt very Conan-like.

It was the kind of chapter that feels satisfying when your prediction lands.

Impression and Theory 2: The Heiji and Kazuha Punchline Was Much Looser Than Expected

After the distance and suggestive wording in File 1157, many readers were probably bracing for a misunderstanding or even a breakup-like turn.

But once the lid came off, the whole point was only that they wanted to say they were dating. The temperature gap made it easy to want to snap back, “That’s all?”

They even forget that Conan was present when it happened. That makes them look so giddy about becoming a couple that it is actually pretty charming.

Impression and Theory 3: Momiji Still Will Not Give Up

At the end, Momiji Ooka recites a waka poem and overlaps it with the feeling that even if things hurt now, the day may come when she looks back on them with longing.

Against the newly dating Heiji and Kazuha, the question is how Momiji will try to step in from here. Whenever Momiji gets involved, the atmosphere immediately becomes more complicated, so her next appearance remains something to watch.

Next Time, File 1160 Appears in Weekly Shonen Sunday Issue 19

The next Detective Conan chapter, File 1160, is “Escape from the Zodiac Mansion” and is scheduled for Weekly Shonen Sunday issue 19.

For the next round, the focus shifts toward predictions and theories for File 1160, along with what may be included around Volume 109.