Ruska is a boy who lives in one part of a massive, tower-like structure which makes up a world that is mostly vertical. Fascinated to learn what lies at the bottom, he acts upon his curiosity when he sees a young girl fall from the sky above, and jumps after her, plummeting into the abyss.
From there, the adventure begins as he comes across many characters and challenges in an effort to reach the bottom and decipher the secret of the Vertical World.
The Vertical World (Tate no Kuni) is an Ontological Mystery series by Kuu Tanaka which began as a web manga submitted to the Jump Rookie site in August 2018 before winning the Bronze Rookie Award and thus earning the right to serialization within Shonen Jump+. All chapters can be read for free on the official MangaPlus website.
Though the series presents itself and its mystery similarly to other series such as Made in Abyss, The Vertical World sets itself apart largely through its tone. Ruska often gets into dangerous scenarios, many even life-threatening - but throughout everything, emphasis is placed on the adventure, the sense of discovery, the many good people he meets, and his determination to make things right. Many of the characters are varying degrees of sympathetic, if not outright Nice Guys, and the series avoids stewing in bleakness for long, no matter how deep the rabbit hole gets.
The other thing that sets The Vertical World apart is its love for scientific concepts, both real and fictional. The story easily scores a 3 on the Mohs Scale of Science Fiction Hardness, tackling everything from time dilation to dark matter but weaving a careful yet surprisingly consistent mixture of hard and soft science concepts to explore its world in a manner that's both fun and genuinely engaging. Even the main characters are affectionately named after various names in science - Ruska owes his name to none other than the physicist responsible for the first electron microscope.
Due to the mystery-heavy Mind Screw nature of the series and the amount of twists present, some spoilers may be unmarked.
Tropes found in The Vertical World:
- Anti-Nihilist: Much of the main cast qualifies, to the point that it's a theme of the series. The characters regularly face major truths about the world they live in, ranging from the knowledge that they live in a fabricated environment to their very existences not being "real", but despite this, only ever see this as a bigger reason to assert their existences.
- Art Evolution: Chapter 1 opens with rough, scratchy linework and simple shapes. Kuu Tanaka's style improves notably over the course of the series, most notable in his attention to people and backgrounds.
- Artificial Limbs: Ruska gains several of these from Zupa over the course of the series, starting with him losing his fingers to the tower. Kepler also has a mostly artificial body, implied to have been the result of catastrophic events in the past.
- Body Horror: The alternate timeline Omega running the wormhole station was physically merged with it, causing everything below her waist to become a fleshy mass of cells that threatens to consume her.
- Badass Normal: Ruska, Omega, and Geezer lack the intellect and tools of their peers as well as the many strange beings in the Vertical World, but are capable of keeping up through a combination of determination and resourcefulness.
- Expendable Alternate Universe: Deconstructed on multiple levels. Ruska's adventure takes him to the past, present, and future across multiple dimensions - despite often meeting multiple versions of people he knows and venturing into multiple realities with varying levels of permanence, he never once treats the people and worlds he comes across as expendable. Once he escapes the Vertical World, Ruska even tearfully calls Chandra out for developing a new history because of how many people were created just to conflict and suffer because of it. It's Ruska's firm understanding that the people within the Vertical World aren't expendable and still have lives that he'd be abandoning once he alters the past that leads to him going I Choose to Stay at the end of the series.
- Ruska's very motivation to save the Vertical World is founded on his refusal to acknowledge this trope, as the people of the Vertical World have lives that could continue indefinitely, regardless of his actions. Despite this, he understands that even if they aren't the exact same people he knows, various versions of the Vertical World and those within it will continue to be created and destroyed unless he can create a timeline without this cycle.
- Fingore: When Omega is "quarantined" away from Ruska, Ruska desperately attempts to grab onto the tower, only to have his fingers removed when the tower closes back up, crushing his hand.
- Gadgeteer Genius: Kelvin is this, having made a robot body for himself with many useful tools, among other things. Zupa also fulfills this role to a lesser extent, though she leans more into The Engineer.
- His Name Really Is "Barkeep": As the party quickly learns, the geezer's name really is "Geezer". Zupa is bewildered, jokingly asking if he's been a geezer since he was a kid.
- I Choose to Stay: Ruska makes this decision at the end of the series, realizing he won't be able to see his friends in the Vertical World once they change the past.
- Jigsaw Puzzle Plot: The series only begins with the knowledge that there's a strange tower-like world, with bits and pieces of the world's nature made more apparent as it continues.
- Never the Selves Shall Meet: In this universe, meeting yourself doesn't affect the universe, but it does cause both versions of you to "collapse" into one, sometimes causing your memories to merge as well.
- Really 700 Years Old: Kelvin is this, as he had been traveling through the Vertical World for at least 500 years, with his robotic body keeping him alive.
- To a lesser extent is Omega, whose body miraculously has not decayed at all despite the amount of time she fell for.
- Star Scraper: The Vertical World appears to be this, stretching onwards in both directions with seemingly no end. Part of Ruska's goal is figuring out what's at the bottom. Turns out there is a "bottom", but it's not connected to any kind of ground - and even more, there's a "true bottom" which represents the edge of the world's reality.
- Stable Time Loop: The last portion of the series is the cast trying to Set Right What Once Went Wrong and break the cycle of events that lead to the creation and eventual destruction of the Vertical World. Their initial attempt fails, simply changing the details but not the result. It's only once they get Omeganium from Kepler that they can go into Earth's past and finally prevent everything from happening again.
- Enrico states that her version of Earth was destroyed by an attack from an unknown civilization, rather than a meteorite, as Chandra recounts. It's later understood when Ruska and company travel to the past through a wormhole and the Omega System's newly constructed Vertical World runs through the wormhole too, piercing the planet before the meteorite was able to.
- In addition, the Omega that travels with Ruska is Risa, the girl whose death lead to the very creation of the Vertical World. Ruska's attempt to save the Vertical World leads it to winding up in a wormhole taking it to the past, where it crashes through the planet in place of a meteorite. Risa falls and merges with the Vertical World's tower, placing her in Ruska's version of the world so that they would meet, while Professor Gluon goes on to create the Vertical World anyway as a result of her death.
- Timey-Wimey Ball: Justified, due to the genuinely complex mechanics behind time and space travel in the series.
- The Vertical World itself for the most part is a case of Stable Time Loop. The way time works inside it means the past, present and future can exist at simultaneous points, making it impossible to alter anything already known to be set in its "future" in some way.
- The simulation inside P.P. is set in the past, but its very existence is stated to have created "new history" and as a result is responsible for the Vertical World's already-established present. Ruska finds that its events can be altered by his own interference, though this doesn't alter the Vertical World's present further so much as create an Alternate Timeline.
- Earth itself can have its history altered through traveling to the past, but for most of the story is a case of You Can't Fight Fate as the party's attempts to change what happens to Earth the first time inadvertently causes the same problem, just with a different context.
- The story as a whole implies much of everything up to Ruska's final encounter with Kepler is a natural, immutable sequence of events that has happened before in some shape or form, and the diverging point that breaks the loop is Ruska's resolving to defeat Kepler and use the wormhole to alter Earth's past.
- Void Between the Worlds: Ruska and his party reach a hole that allows them to access a place that seems like this. It's quickly revealed this void is in fact the universe outside of their own.
- Year Inside, Hour Outside: Not only is the Vertical World infinite in theory, but time itself travels at an infinite rate in comparison to the outside world. Among other things, this means the world's past, present, and future are connected to each other, even across multiple timelines. Ruska uses this knowledge to justify his I Choose to Stay moment, citing that even if the current timeline's Earth is minutes away from destruction, the Vertical World is infinite, and so he and his friends could exist within it for eternity.
