Monkey D. Luffy's progression throughout One Piece has seen him become one of the most fearsome pirates on the seas. Thanks to the powers of the Gomu Gomu no Mi, Luffy has mastered several powers in the form of gears over the years.
Right now, his strongest gear by far is Gear 4, by virtue of which he's defeated the likes of Doflamingo, Cracker and even Charlotte Katakuri. With its ferocious power only proving to be deadlier with each passing arc, Gear 4 has certainly served its purpose extremely well in the story. Here are 10 things you probably didn't know about Luffy's Gear 4th technique.
10 Its Development
Monkey D. Luffy came up with the idea of Gear 4 during his two-year training at Ruskaina, the island of 48 seasons. With the beasts inhabiting the island proving too difficult to defeat, Luffy resorted to using Gear 4 to overpower them and succeeded in doing so quite well.
With time, his usage of Gear 4 has improved significantly with Luffy now being able to use it without many of the drawbacks that he faced initially. It is only going to get stronger with time, especially with the threat of Kaido and Big Mom looming over Luffy's head.
9 Its Mechanics
Every gear of Luffy sees a specific property of the Gomu Gomu no Mi coming into play. In the case of Gear 4, Luffy relies on the power of elasticity and compression that his Devil Fruit offers. After blowing air into his muscles, Luffy is able to compress his power using Busoshoku Haki.
This, in turn, increases the elasticity significantly, giving him more speed and power. According to Silvers Rayleigh, this is a very clever way to deal with enemies and it also enables Luffy to fly, which is yet another advantage that Gear 4 offers.
8 The Tribal Tattoos
Luffy's extensive usage of Armament Haki on his body to maintain Gear 4 leads to the formation of tribal tattoos. Other than Luffy, characters such as Charlotte Katakuri and Big Mom have also showcased the ability to use Haki with Tribal tattoos.
Although it's significance hasn't been explained yet, we believe that it has to do with the power of Haki and Devil Fruit essentially combining, instead of simply coating haki over the body of the user. This can be backed up by the fact that Luffy's body remains rubbery in Gear 4 despite being hardened with Armament Haki.
7 His Height
Among many other things, Luffy's height is also affected by his usage of Gear 4. At the age of 17, Luffy was around 1.72 meters tall. During the two-year time-skip, Luffy grew slightly to 1.74 meters. However, this is nothing compared to how much he grows when he uses the ability known as Gear 4.
From what the manga suggests, Luffy grows more than twice his height, towering above most with a height of about 4 meters. The exact height of Gear 4: Boundman isn't known, but it is likely around the above-mentioned figure.
6 His Metabolism
Although it may not appear to be so on the surface, Luffy's Devil Fruit is extremely taxing on his body, and it leads to him burning up a lot of energy extremely quickly. Just like Gear 2, Luffy's Gear 4 see him burn an incredible amount of energy in a very short period of time, as seen after his fight against Charlotte Cracker.
Even though Luffy stuffed himself with innumerable biscuits to the point where he became bloated, using Tankman burned it all up within a matter of minutes. Expectedly, even Nami was surprised at how much his metabolism increases after using this power.
5 Its Disadvantage
Gear 4 grants Luffy with a significant boost to his speed and strength, thanks to the power of compression that his Devil Fruit offers among many other things. Unfortunately, there is a disadvantage of this ability, especially when it comes to the go-to Boundman form. Luffy's range is severely decreased due to the attacks being based on the ability to compress rather than stretching.
Thankfully, Luffy's counter to this problem seems to lie in using a different form of Gear 4, called Snakeman. Using its powers to stretch nearly infinitely, Luffy is able to make up for what Boundman lacks. However, in this case, his power isn't as high as it is in Boundman.
4 Its Color
Boundman sees Luffy coat himself in Armament Haki, which leads to his body gaining a black coating on the parts where he uses this ability. In the anime, the black color of Haki is further given a reddish tint. Although Oda's version of Gear 4 coloring initially differed from what was seen in the anime, it seems that he adapted to what the anime did later on.
On the cover of Volume 89 of the One Piece manga, Luffy's Snakeman can be seen with the same reddish tint that we saw in the anime. Whether Boundman will have the same color or not remains to be seen.
3 Its Forms
Unlike the other gears of Luffy, Gear 4 had several applications that Luffy uses via different forms. In the fight against Donquixote Doflamingo, Luffy unveiled the powerful Gear 4: Boundman. Initially, fans believed that Boundman was all Gear 4 had to offer.
However, this was soon proven wrong when Luffy unleashed Gear 4: Tankman (Full Version) against Charlotte Cracker. Its regular version remains to be seen to date. In his fight against Charlotte Katakuri, Luffy relied on speed offered by Gear 4: Snakeman.
2 The Inspiration
According to Eiichiro Oda in One Piece Volume 79's SBS, Gear 4 is inspired by the Buddhist guardian entity known as the Nio Statue. In the SBS, Oda explains that Luffy intends to protect things important to him, and this is where the inspiration comes from.
Furthermore, the Nio Statue has a ribbon surrounding it, which is similar to what Oda has done with Gear 4's steam. From what we've seen, the steam that's generated by Gear 4 takes a similar shape around Luffy's body.
1 Its OST
Although Luffy has had a number of forms over the course of the series, Luffy's Gear 4 is the only form so far that has been given an original soundtrack by the team that handles the anime. The OST for this form is simply known as 'Gear Fourth'. It is also available as a part of the One Piece New World Original Soundtrack.
A slightly different version of this theme was played when Luffy entered Snakeman to fight against Charlotte Katakuri towards the end of the Whole Cake Island arc. It goes without saying that both the OSTs are extremely well-made!