Rank: Shōkin Kasegi (probably best although he's not really a stealth-type)
History: His former village is unknown, unimportant, and probably destroyed at this point. However they were fighting over various pieces of technology due to their shinobi being shit at actual jutsu n' stuff. Nanatsu was an exception as he was not shit at ninjutsu and specialized in explosions or lasers or somethin.' Anyway, one day his daughter was out playing in the street and he accidentally blew her up! He was taken to the village's technological research facility where he was decked out with some top-of-the-line technology stuff. Years later Sadame found him. And he joined because it is suggested that he hates what technology has turned him into (a monster). The end.
Abilities: Alright, bear with me here. Nanatsu is a humanoid weapon, meaning he is more machine than human at this point. As such, he functions as a self-contained EMP generator. He can produce waves of chakra-induced electromagnetic energy, which means he can shut down surrounding technology (highly useful for Sadame) as well as short-out some kinds of ninjutsu (aka, lightning-based attacks). He can disrupt and intercept electronic communication, crush armor made out of metal, etc. He also has a limited control over gravity, but mostly uses this technique to paralyze enemies by magnetizing them to the ground, after which he approaches them slowly, slowly, slowly until he is close enough to do whatever he wants to them (mwah hah hah). People effected by his powers will find they have most sound around them completely blocked out, which kind of suggests he is a walking, refined version of a Shijima (see: Scientific Ninja Tool). He can also create a version of the Absorbtion Sphere using his EMP powers.