Project ARMS Vol 1

From the VIZ Media edition

Ryo Takatsuki appears to be a normal high school student - he's smart, independent-minded, and the other kids look up to him. But recently it seems everyone is after him! Ryo is pulled from his ordinary life when he learns that a mysterious organization has replaced his arm with a powerful nanomachine-driven weapon called Arms. A group of special agents is out to get him, and his best friend Katsumi is missing!

Source: Anime News Network Encyclopedia