Ryo Takatsuki injured his right arm in an accident years ago. The resulting surgery brought about some unexpected, but not entirely unwelcome changes -- enhanced healing along with the presence of a superweapon dubbed "ARMS" in his body. But with all power comes a price, and with newfound allies who share his predicament, he must battle a secret organization trying to control the ARMS while trying to find the truth behind the weapon in his body for himself...
Two and a half years have passed since the end of Naruto’s old adventures. He has trained hard with Jiraiya-sama and has returned to Konoha to reunite with his friends; but Akatsuki, the organization that threatened Naruto years before, is on the move again and this time Naruto is not the only one in danger. With the powerful Akatsuki organization looming ahead of him, Sasuke still missing, and the struggle with the beast hidden inside him a continuous battle, will Naruto's hard-earned improvements be enough? Join Naruto, Sakura, new friends and the rest of the old gang as the action heats up with new techniques and stronger enemies.
The main characters and storyline are somewhat similar in these two tails. In Naruto, you have Naruto, who struggles with the burden of the 9-tailed fox sealed within him. In Project ARMS, you have Ryo, who must deal with the terrible power of the ARMS Jaberwock contained within him.
During their respective series, they both gain numerous friends while progressing towards their goals. Obviously, they both also have a number of epic battles with those who impose them.
Some years into the future, a strange, unexplainable natural disaster has broken off a piece of the Japanese mainland. Known as the Lost Ground, it is now inhabited by people with Alters -- machine-like extensions of their own will. In order to keep the peace on the Lost Ground, the HOLY organization uses its own Alter capabilists to police the region. In the midst of the chaos is a young man named Kazuma, whose life will soon change forever as he discovers his hidden abilities, and how to wield them.
Project ARMS and s-CRY-ed have a very similar feel and tone. In each, several characters have special abilities and as a result are subject to a degree of persecution by some people, while others attempt to use their abilities to their own end. There are plenty of fights between individuals with special abilities in each, all of which are pretty exciting. Both are solid series, so if you enjoyed one, you are sure to like the other.
Date Kyosuke is a young man with problems. After being stabbed by his beloved mother, he discovers he has a long lost sister -- Runa. She is the first of many relatives that he and others in the story find tied into the seeming chaos of their lives. Date embarks on a quest to find Runa, aided by his new ability to turn into a monster; all the while in pitched battle at almost every turn with agents of mysterious organizations.
SoulTaker reminds me of Project Arms to a degree. Mostly, the SoulTaker entity that the main character can transform into reminds me of Jabberwork from Project Arms. Add in some post/near-apocalyptic feel and a secret organization out to get the main character(s), and you have a firm basis for comparison.
I did feel that Project Arms had a better overall story however. If you enjoyed Soultaker, I recommend giving it a try. If you enjoyed Project Arms and don't mind a somewhat weaker series, feel free to give Soultaker a try.
Shou Fukamachi is just an average high school student,until one afternoon, Sho and his friend Tetsuro stumble upon what looks to be a landmine, which Sho accidentally activates. Instead of attacking and killing him, it grants him control of the Guyver, a powerful biological armor, which the evil corporation Chronos wants to take at any cost, even if it means killing Shou and his friends.
Yusuke Urameshi was a normal middle school punk until he was hit and killed by a car, while saving a child. His selfless action earned him the right to gain his life back and serve as a detective of the spirit world, keeping the world of the living safe from a myriad of demons. But being reborn has its price: Yusuke must hatch a spirit beast that will develop according to his actions, and if he doesn't act in a good and honest manner, it will eat his soul. Can Yusuke protect the human and spirit worlds and still manage to save himself in the process?
In both Yu Yu Hakusho and Project Arms the main characters are a group of 4 youngsters with special abilities. They fight the evil, and are often told they can't win. They start out weak and grow stronger. Both series also have a lot of sarcasm.