Naruto has been a very successful and influential anime franchise over the last two decades. Of course, it was also influenced by a variety of other stories and brands, the most obvious being historical ninja lore. One thing that some fans might not expect is the mecha series that influenced one of the characters.
Kakuzu was a member of the wicked Akatsuki, and his abilities granted him a morbid immortality. He also had attacks that were greatly influenced by the Mobile Suit Gundam series, namely the original classic anime. This demonstrates how popular Gundam was and still is, with Naruto author Masashi Kishimoto pulling inspiration for Kakuzu from his fandom. Here's how the zombie assassin infused the realm of shinobi with the spirit of huge robots.
Naruto's Kakuzu Attained Immortality Using the Most Reprehensible Methods
Kakuzu debuted in Chapter #312 of the Naruto manga, with the anime adaptation of these chapters -- Naruto Shippuden -- bringing him in at Episode #71. A denizen of the Village Hidden by the Waterfall, Kakuzu was once tasked with assassinating the first Hokage. This ended in failure, however, leading to his being disgraced among his village. In revenge, Kakuzu killed the leaders of his village and consumed their hearts, unlocking a method of becoming immortal through the life-forces of others. From there, he would join the organization known as the Akatsuki, though his allies would many times become his enemies.
Kakuzu's lack of sympathy and patience will lead to the deaths of several of his Akatsuki companions throughout the years. He was eventually matched with Hidan, who had a similar form of immortality, as a joke. Thus, much to Hidan's disgust, Kakuzu's violent outbursts would never result in his death. Nonetheless, he was a remarkably cunning ninja, even taking on the mighty Kakashi and had a speed that made him nearly hard to track. Another element that is difficult to notice about the character is his influences, which have little to do with ninjas and everything to do with the premier Real Robot mecha anime series.
The Greatest Mecha Anime Series Inspired Naruto's Kakuzu
Many of Kakuzu's attacks in Naruto are named after Gundam Mobile Suits, specifically the first entry in the Universal Century chronology. The Earth Grude Fear (Jiongu) attack, for example, is named after the Zeong unit and transforms the user's body into a conduit for huge black tentacles. It also mimics that mech's capacity to detach its arms offensively in several ways. The Earth Release: Earth Spear attack is also known as Domu, after the Mobile Suit Dom. Z'Gok inspired the name of the Fire Release: Intelligent Hard Work attack (Zukoku).
This all makes sense given how much of a fan Kishimoto was of the classic Real Robot series in his youth. According to the mangaka, he would draw his favorite Mobile Suits all the time when he was younger, with this early fan art honing his skills and allowing him to go on and develop Naruto as an adult. Of course, these elements are easy to miss in the finished work, especially if viewers aren't in-tune with the names in the Gundam franchise.
Ironically, there would even be an Akatsuki Gundam unit in a later entry in that franchise. Regardless of whether the reference was noticed, the ruthless Kakuzu existed as a giant homage to the mecha anime, showcasing how much it permeated Japanese pop culture.