Raijin

and his brother Fūjin are the Legendary Stupid Brothers.

Background
The two brothers originated from an unknown village. They once killed their comrades over a meal, and calmed down immediately afterwards. After the incident, they were locked up in Konoha Strict Correctional Facility, though the ones who apprehended them struggled with their mighty strength. At some point in their past, they had an encounter with Tsunade and the brothers have been terrified of her ever since.

Personality
Raijin and his brother's thoughts revolve completely around food, and the guards of the prison would use this to their advantage, by controlling the food supply to keep the brothers in check. When dispute over food comes up, the two can act with tremendous rage and violence, killing anyone who ruins their meals. Both live up to their monikers as being very unintelligent, and they were scared into submission by Tsunade. He relies on his older brother's opinions whenever they run into something they could not comprehend, to which Fūjin replies with rather foolish answers. The same goes for any silly questions Raijin may come up with.

The two brothers have a deep sense of affection for each other, as each of them suspect something wrong when Ino Yamanaka took over their minds to attack each other, and tried to snap the other one out of it. They also seemed to have developed an attachment for Mizuki, because he went out of his way to get food for them, and claiming an even better feast awaits them at Orochimaru's place. However, when Tsunade threatened them with no dinner if they do not return to the prison, they immediately forgot all about Mizuki as they rushed back.

Abilities
Both brothers have monstrous strength and stamina, only increasing to higher levels as they get angrier. Also, with their power, they are able to jump great lengths and run at high speeds. Their strength has been said to be comparable to that of Tsunade's. However this is proven wrong when Tsunade effortlessly defeats them both by merely flicking them both in the head, sending them both flying back several feet. Consequently, the prison they reside in is incapable of containing them, as they can easily break down the cell door. When even Shikamaru, Ino, and Chōji held them in their Shadow Imitation Technique, Mind Body Disturbance Technique, and Partial Multi-Size Techniques, they were able to break out with brute strength alone. However, for all their strength, they are unintelligent and can be easily duped.

In addition to their brute strength, both brothers have shown be to impressively resistant to damage. They were able to easily take blows from each other, and Tsunade, without any sustainable injury.

Mizuki Tracking Mission
While in prison, the brothers were befriended by Mizuki, who convinced them to help him escape by offering them food. Once they escaped, they fought Naruto and the members of Team 10. They were unable to beat the brothers, and it was not until Tsunade arrived and threatened to not give them any more food that they returned to jail.

Trivia

 * Raijin shares the same name with the Shintō god of thunder.
 * Raijin's prisoner number is 13.