From der wiki:

Nearly half of the cast revealed during beta testing are new comers to the series. Characters Killian and Rimururu were revealed to players during the second phase of beta testing in December. On January 17, 2008, two characters were listed on the Japanese official site. Each character has their own stats sheet, sample moveset, and backstory. Since then, the site continued to update in the same fashion on a weekly basis. In the All Nippon Amusement Machine Operator's Union (AOU) 2008 event, a new fighter Claude and Yagyu Jubei were revealed.

Takechiyo, Suzuhime, Angelica, Gallows, J, Kim Hye-Ryen, Valter, Sugamata Jinbei, Black Hawk, Killian, Claude, Golba, Draco

Some characters are homages to traditional swordplay (a Korean spear fighter Kim and elderly spear-wielding samurai Jinbei) while other characters take contemporary and artistic liberties (J, an afro samurai and Gallows, an axe wielding Viking). Confirmed characters from previous game titles are:

Haohmaru, Nakoruru, Hattori Hanzo, Galford, Tachibana Ukyo, Wan-Fu, Senryo, Kyoshiro, Charlotte, Yagyu Jubei, Kibagami Genjuro, Rimururu, Kazama Sougetsu, Kazama Kazuki

Since they bring it up, there is actual historical prcedence for a black samurai (not so much the afro part). In 1581 Nobunaga Oda, the first of three unifiers of Japan, met a black slave traveling with an Italian Jesuit. Since Nobunaga loved unique things from foreign countries, he took an intense interest in the man, giving him name of Yasuke and making him a retainer. As a samurai, Yasuke served Nobunaga faithfully, and when his lord was attacked by a turncoat general at Honnoji Temple in Kyoto, Yasuke went to assist Nobunaga's son, and fought very bravely. He was eventually captured and turned over to the Jesuits, and no further mention is made of him after that.

And now, a 2nd trailer: