Kuutei Dragons, like Deca-Dence, is set in a world where people harvest monsters for both food and fuel, in this case the titular dragons. The story follows a crew of dragon hunters, or drakers, aboard the airship Quin Zaza, specifically newcomer Takita who not only looks a lot like Natsume from Deca-Dence but has your fairly typical genki-girl protagonist personality along with a great capacity for memorable faces.

She’s also mentored by an older male crewmember, Mika, who while more over-the-top than his Deca-Dence counterpart, has a similar dynamic. Like the Gadoll, the dragons in Kuutei Dragons have pretty strange and interesting designs and are part of some solid action sequences. There’s no huge twist like in Deca-Dence and much more time is spent on the ‘eating the monster’ part of the world with some strangely appetizing dragon dishes. For your information, Kuutei Dragons is also a fully 3DCG anime, and sometimes arguably feels a little too similar to real-world whaling, and is certainly a series worth checking out for Deca-Dence fans who appreciate its world-building.

Set in the distant future, Gargantia on the Verdurous Planet follows a young genetically-engineered mech pilot named Ledo who is part of an interstellar war against hordes of bizarre, squid-like creatures called Hideauze. During one battle, Ledo and his sentient mech, Chamber, get flung into the far reaches of space until eventually crash-landing on Earth which has become almost completely covered by a vast ocean. After he and Chamber are discovered by Gargantia, a fleet of scavenger ships, he must then learn to adjust to this new world and begins to uncover mysterious connections to his own old life in space.

Compared to Deca-Dence, Gargantia has a similar feeling with the whole mobile-fortress concept, in this case being the titular fleet of ships, and the struggle against a seemingly overwhelming, monstrous enemy. Without spoiling much, there also is a bit of a twist in the story but overall it’s just a solid sci-fi action series with similar ideas explored in its setting and the addition of rad, and personable, mech in Chamber that make it a good recommendation for Deca-Dence fans.

Swap out an endless ocean with sand and a fleet of ships with a mobile island called the Mud Whale and you have the world of the Children of Whales, but there’s more to. Somewhat similar to Deca-Dence’s Tankers and Gears, the society on the Mud Whale is divided into the Marked and Unmarked who are people able to use a psychic power known as Thymia but have reduced lifespans and more normal-lived people without powers respectively.

The story follows Marked archivist Chakuro who is obsessed with recording everything and a mysterious girl he and his friends encounter on a new island that will change their lives forever. Although more fantasy and mystery than sci-fi action, Children of the Whales’ world with its rigid class structure and humanity aboard a giant moving vessel is certainly similar to Deca-Dence’s titular fortress. It also has its own strange creatures in the Nous to boot which is why it fits nicely on this list.

Launching us squarely into “the world is a game” terrority, Accel World takes place in the future year of 2046 where augmented and virtual reality are commonplace thanks to widespread collar-like Neuro Linker computers that can wirelessly connect to users' brains to easily bring them into VR and AR. The story follows Arita Haruyuki, a comically short and fat middle school student who is bullied and lacks self-confidence but is highly skilled at games—VR racketball, at least. He unexpectedly is contacted by the popular and beautiful student council vice-president who introduces him to a secret game called Brain Burst that can let users jump outside their bodies in the real world by accelerating their brain waves so quickly that time almost stops and play an eerily intense and lifelike VR fighting game of the same name that will remove this power if a player runs out of points.

Although arguably not super similar in terms of overall feel, Accel World does explore some of the same concepts as Deca-Dence that should appeal to those fans, particularly if they are also interested in some very anime school romance subplots. Also some pretty good faces from Haruyuki to be seen!

Perhaps trying to one-up Accel World’s universe with the series’ super-advanced VR MMO arriving in 2043, the titular Infinite Dendrogram is the first game that can perfectly simulate all of the five senses for its players and has “infinite possibilities” largely thanks to each user being given an in-game AI companion called an Embryo with unique powers and personalities that change as they level up. The story follows newbie Mukudori Reiji and his more experienced older brother Shuu as they adventure through the world of Infinite Dendrogram.

Although this series is not a masterpiece by any measure, it might be a good recommendation for Deca-Dence fans who enjoy the sci-fi game aspect and real people interacting with advanced AIs but are looking for something more light-hearted with more cute girls and some wacky characters like Shuu’s cool, machine-gun-wielding bear avatar.

Although it’s the third season of the popular, often contentious, Sword Art Online series, Alicization is surprisingly fairly easy to jump into without having seen the previous installments as it goes over the basics for newcomers, but is it worth watching for Deca-Dence fans? A solid maybe. Sword Art Online game survivor Kirigaya Kazuto, aka Kirito, finds himself in yet another game called Underworld and begins to question his own identity. This new world is created using Soul Translator technology which connects a person’s spirit/consciousness directly instead of through the brain, making it feel even more real. Kirito finds his memories being continually erased save for a vague recollection of the name “Alice”.

Without spoiling much, Alicization is best connected to Deca-Dence in its exploration of AI characters which blur the lines between them and organic life with explorations of their own free will and morality. It’s still SAO but goes in some more interesting directions and notably nerfs Kirito’s overpoweredness to give more room for new deuteragonist Eugeo. It also has solid action and production values that Deca-Dence watchers should appreciate which overall makes it worth checking out for fans.