A boy gets involved in an accident when in kindergarten, horribly damaging his arm, but the doctors somehow manage to save it. Now, several years later, his arm seems to be becoming the focus of strange events as it turns out to be more than a normal arm. Meanwhile, a secret organizations is out to get hold of him and the power he possess.

The 2nd Chapter continues the story of Ryo Takatsuki and his companions' quest to discover the secret of the mysterious A.R.M.S. they all possess and what the future may hold for them. They now know where the answers lie but to get to them, they must fight a desperate fight of survival against a powerful military corporation that wants their secrets no matter what the cost.

[Source: AniDB]