Sorry I wasn't able to post more detailed earlier. Here's a translation of the characters introduced so far:
Shu Ouma - 17 years old. The main character. His right hand holds a special ability - The King's Power. He is able to extract something known as "Void" from his allies. "Void" is a physical manifestation of a person's personality, and can take the form of a sword, or a musical instrument, or a camera. To apply this ability in combat, he has no choice but to make friends.
Gai Tsutsugami - 17 years old. Young leader of the "Undertakers" gureilla organization. He has great charisma and physical strength, and pilots the Jeet Kune Do.
Inori Yuzuriha - 16 years old. She is the voice of the internet artist Egoist. She is also a member of the "Undertakers".
Tsugumi - 14 years old. She's an excellent hacker who serves as the operator for the "Undertakers".
Ayase Shinomiya - 17 years old. A wheelchair-bound girl who pilots End Rave for the "Undertakers".
Edit: Here's a 2meg scan of the full color character designs. That's Gai, Inori, and Shu:
http://imgur.com/n2xKN
Edit2:
http://myanimelist.net/forum/?topicid=300032&show=0