Tower Dungeon is a Dark Fantasy manga by Tsutomu Nihei (of Blame! fame), which started serialization in 2023.

The series is set in a fantasy kingdom whose princess was kidnapped by a mysterious shapeshifting entity posing as the king. The Kingsguard sets off to rescue her by going to the Dragon Tower, a massive floating building infested with monsters, undead, and other threats. Yuva, a strong farmboy from a small village, is made to go with them when recruits are collected to fill in for injured Kingsguards.

Yuva, now a part of a special squad of the Kingsguard created to rescue the princess, must face the strange and dangerous tower with all of its bizarre lifeforms and monsters guarding the way up, even while several other factions also grow interested in the rewards for saving the princess.

Tropes

• Cat Folk: They're called Nyabilians and they aren't seen much in the rural provinces, causing Yuva to stare when he sees one.
• Damsel in Distress: Yuva's sister is targeted by a very dangerous man, Marquess Karash, which requires Yuva and Garamna swear to protect her.
• Dungeon Crawling: The plot essentially takes place inside a gigantic dungeon, filled with monsters and treasure to loot. In a lampshading, Lilisen casually starts breaking pots open in Chapter 3 looking for valuables.
• Elemental Personalities: Lilisen is a fire mage with a fiery temper to match.
• Expy: Marquess Karash is one to Count Dracula. They're both powerful noblemen who watch over a village from where many people get taken away mysteriously because said noble feeds on them. They also both have an imposingly tall figure that turns into a monstrous form for fighting. Karash being able to transform into a dragon creature may itself be a reference to Dracula also being associated with dragons.
• Humanoid Abomination: The guardian of the 50th floor, the Chymus Insect, is a giant, floating monster whose body looks like a mix of a woman with an insect, with a bulbous neck from which more insect-like eyes come out.
• Inter-Service Rivalry: The Kingsguard and the Parliamentary Guard don't like each other very much.
• Mega Dungeon: In the usual Nihei fashion, the titular tower dungeon is a megastructure. The tower is 3 kilometers wide, and taking that into account, around 15 kilometers tall. Each floor is also stated to be on average 10 meters high, meaning that there's potentially over 1000 floors of dungeon to explore!
• Noodle Incident: The presence of undead and shortcuts between floors make clear that people first tried to conquer the Dragon Tower a long time ago, even though it was only recently called down from the sky. The circumstances of these first efforts remain unknown.
• Power Floats: The head of the Parliamentary Guard, Miligoa, has no arms or legs and floats in the air of his own accord. He's also a powerful magic user.
• Recurring Element:
  • As with other Nihei's works, the protagonist is a quiet man exploring an incomprehensibly massive location filled with impossibly huge monsters.
  • The Armored Gateman has the same emblem as the Safeguard and the Regenerated.
• Running Gag: Ledges and walls keep giving way whenever Yuva puts his weight on them, and he keeps accidentally discovering new areas of the tower as a result.
• Save the Princess: The central premise involves rescuing the princess. That being said, she seems to be very calm about the whole ordeal, and when she shows up, she assures the main characters that she can't be killed until the villain reaches the top of the tower, so they should focus on the enemy they're fighting.
• Standard Hero Reward: Supposedly the reward for rescuing the princess is her hand in marriage.
• Succession Crisis: With the kidnapping of both the King and Princess Ignelia, the second in line, Minserbel, is forced to take the throne despite her wish to be part of the effort to rescue her sister. She returns to the capital, but creates a new unit made of the Kingsguard's rookies to keep going after the princess in her stead.
• Super-Strength: Yuva has a bizarre superhuman strength that surprises anyone that sees him lift anything.
• The Tower: The Dragon Tower is an inhumanly massive structure (three kilometers wide, and many times taller) that pierces the atmosphere and reaches space, populated by all manner of creatures and monsters.