The world of Japanese animation is widely beloved, and sometimes gently mocked, for its use of countless conventions, tropes, cliches and running jokes, and some anime series are actually self-aware when it comes to these well-worn ideas. One of them is the concept of "hammerspace," which breaks the laws of physics in a big way.
For the most part, hammerspace is used as a visual gag rather than something serious, and on some levels, it's not even meant to be taken literally. Many anime and manga franchises make occasional use of hammerspace, but more recently, some anime series have reinvented hammerspace as a legitimate combat technique, complete with a set of rules and restrictions. Pulling objects from thin air has never been more fun.
The Origins & Comic Uses Of Hammerspace In Animation
The concept of hammerspace is best-known in the realm of Japanese anime today, but it wasn't born there. Instead, the basic concept dates back to the early to mid-20th century of Western animation, such as MGM and Warner Bros. productions. In those days, characters could use hammerspace by producing any desired item out of thin air from just off-screen -- probably so viewers wouldn't have to see the items literally coming out of nothing. That made it easier to suspend disbelief while watching these cartoons, and characters could assemble tools, various cooking implements or even weapons out of nothing. At the time, no one actually used the term "hammerspace" to describe this.
Later, closer to the 21st century, Japanese anime fans began describing this phenomenon as hammerspace, which was usually used for visual gags rather than a serious combat system or important plot device. The classic image of hammerspace involves a female character producing a large wooden mallet from thin air to strike someone on the head as punishment for something they said or did, or was believed to have said or done.
The character Akane Tendo in the Ranma 1/2 anime makes extensive use of hammerspace, to the point of it becoming her trademark, and that's just one example. More recent anime shows use comedic or half-serious use of this concept, such as the young demon Valac Clara conjuring items from thin air out of her skirt's sewn-on pockets in Iruma-kun. Clara doesn't even need energy to produce full-sized vending machines or food -- she just pats her pockets twice and the items come out.
Formal Variants Of Hammerspace In Modern Anime
Some modern anime titles reinvent the concept of hammerspace and incorporate it into their combat systems, complete with rules and restrictions. Perhaps the most famous example is the creation hero Momo Yaoyorozu of My Hero Academia fame, a student hero who can produce non-living items and objects from her skin via her Creation Quirk. Momo can even create functional tracking devices, gas masks, stereo sets, cannons and night-vision goggles with her Creation Quirk, making her a flexible support hero who puts her genius IQ to good work. As a formal combat move and not just a visual gag, this use of "hammerspace" has restrictions, such as the use of lipids as fuel and Momo needing to expose her skin to produce the items. Unlike Valac Clara, Momo cannot create any organic materials, much less candy or snack items.
Erza Scarlet, a major character in Hiro Mashima's Fairy Tail franchise, also uses a variant of hammerspace in her fighting style. Erza wields spatial magic, which allows her to access a pocket dimension where she stores all her armored suits and swords. In battle, Erza can spend a few seconds to re-equip herself with anything from her inventory, almost like a Sailor Moon transformation, and adjust to her enemy's tactics. Even with her massive strength, Erza would struggle to lug along all of her equipment into battle and change suits as needed. Instead, she uses weapons-grade hammerspace to quickly and easily customize her outfit and weapons, all thanks to the magic of anime.