Due to the nature of this story, all spoilers from the original Dr. STONE will be unmarked.
Dr. STONE: 4D Science is a three-chapter Sequel Series to Riichiro Inagaki and Boichi's manga Dr. STONE. Its first chapter was released on November 5, 2023, and it ended on December 24 the same year.
Following the events of the original story, Senku, Xeno, and their friends have managed to revive humanity from the mass petrification event and gain the assistance of a Why-Man. Now, they're looking at a science project so monumental, it dwarfs everything else they've accomplished so far: building a Time Machine that will allow them to stop the petrification before it ever happens. Along the way, they'll have to come up with new applications of the Why-Man to go beyond modern technology—all while investigating a mysterious signal from the future.
Tropes:
- Ambiguous Ending: The story ends with Why-Man admitting that it faked the future message from Byakuya, hoping that this would motivate humanity to create the time machine. However, it promises that if said time machine ever does get completed, it will use it to petrify Byakuya in the past so he can be found and revived in the present. Senku and his friends then dig up Byakuya's grave in hopes of finding his petrified body. The last panel doesn't show what they find in the grave, but it seems to be more than a simple hole in the ground.
- Book Ends: The first chapter starts with kid-Senku setting up an antenna in hopes of receiving a message from his time-travelling future self. This fails. The chapter ends with Chrome getting the idea to set up the same scenario after learning that the time machine can be used to send messages into the past. This time, they do get a signal... from Byakuya Ishigami, Senku's father.
- Chekhov's Gun: In the final arc of Dr. Stone, a single strand of petrified hair nearly sabotaged the spacecraft to the moon when it got trapped in the circuit board and short-circuited it. In chapter 2, Senku recalls the incident when the Kingdom is discussing the material for the space elevator's main thread, coming up with the idea of petrifying organic material (first hair, then silk) to create a light and super-strong material. The petrified hair damaging the circuit board also reveals it to be a strong conductor of electricity, which can be used to power a linear motor car to carry supplies and passengers up and down the elevator.
- Close on Title: The first chapter's title, "Future Message", is shown on page 45 of 47.
- Facepalm: Played for Drama; when Senku realizes the message from Byakuya was a lie, he facepalms in a moment of disappointment and despair.
- Foreshadowing: The first chapter shows the Why-Man learning about humanity and how to motivate them towards a goal. The second chapter gives more details about the petrification beam, such as how it is used on one kind of life form at a time and is invisible to all other ones. This is followed by The Reveal that the Why-Man faked the message from Byakuya to get Senku fired up, by shooting a coded petribeam on mosquitos in the region without anyone noticing.
- Grey Rain of Depression: In Chapter 3, it starts raining when the Why-Man asks to be brought to a vantage point to map out Treasure Island. During this time, the Why-Man turns off its Emotion Suppression, allowing it to feel sadness as it explains how We Are as Mayflies and it will inevitably end up seeing all of its human friends die. The raindrops dripping down the Why-Man's casing resemble tears in one panel.
- Inelegant Blubbering: At Chrome and Ruri's wedding, Kokuyo ugly-cries with Ocular Gushers from his eyes and snot from his nose. The Why-Man asks Gen why he reacts like this.
- It's Been Done: For once Subverted for Chrome after he presents his and Suika's idea for a climbing wire held up by the Earth Rotation, which Senku recognizes as a Space Elevator. Chrome is baffled that another new idea of his was already invented in the 21st century only for Senku to confirm that is was just a concept as 21st century technology wasn't able to build it.
- Manipulative Bastard: Out of non-malicious intentions, the last Why-Man on Earth manipulates Senku and his comrades into pushing onwards with the plan for a time machine by faking a message that supposedly comes from Byakuya in the future.
- A Minor Kidroduction: The first chapter opens with Senku as a kid, setting up a radio antenna on New Year's Day and saying that if he ever manages to build a time machine, he'll send a message back to himself at this moment. However, no message ends up arriving.
- My God, What Have I Done?: The Why-Man, after turning off its Emotion Suppression system, regrets faking Byakuya's future message.
- Not So Stoic: Senku becomes quite disturbed and disappointed when he realizes the message from Byakuya was fake, since he was that much hopeful to have fallen for what should've been an obvious lie. He calms down to his usual self upon confronting the Why-man about it.
- Obstructive Bureaucrat: The first chapter shows international politics getting in the way of Senku and Xeno's plans for time travel. After everything they accomplished in a few years while civilization was frozen, Xeno can't help but want to just petrify all of those politicians again.
- Riddle for the Ages: Chapter 3 possibly turns one scene in the prequel on its head: did Byakuya actually see the light of the International Space Station, or did he see the petrifying light of the Why-Man who was sent from the future?
- Right Behind Me: After the Why-Man and Ryusui argue about whether to tell Senku about the fake message from Byakuya, Ryusui turns around and finds him already in the room, with an uncharacteristic look of anger on his face.
- Space Elevator: Chapter 2 has the Kingdom of Science construct a giant elevator to carry supplies into space for their moon base. Building such a contraption would be impossible using modern science, as the cable would be so heavy that it'd collapse under its weight. However, the Why-Man is able to create a suitable material: petrified silk from silkworm cocoons, which is not only durable enough to handle stress but also works well as an electricity conductor.
- We Are as Mayflies: In Chapter 3, the Why-Man discusses how unbearable it is for it, an immortal mechanical life form, to grow attached to mortal beings whose whole lives represent only a brief blip in its history. It's equipped with an Emotion Suppression system to make the pain of losing everyone it ever grows attached easier to endure.
- Wham Line: The first chapter ends with the time machine receiving a Morse code signal from the future... coming from someone claiming to be Byakuya Ishigami, Senku's father."Hello to you all, denizens of the past. My name is Byakuya Ishigami."
- What Is This Thing You Call "Love"?: The Why-Man is perplexed by Kokuyo's Inelegant Blubbering at Chrome and Ruri's wedding, and asks Gen why "humans expel the eye-water". This leads the Why-Man to lie to humanity, faking the message from the future to motivate them to work harder, because it doesn't understand why this would be seen as unacceptable behavior if the lie does end up being beneficial overall.
- What the Hell, Hero?: In Chapter 3, the Why-Man gets called out for faking the message from Byakuya.
