It's been three years since Yoshitune Minamoto and Benkei Musashibo, warriors of the Genji Clan, defeated the Heishi Clan in a war over the "Amahagane". The Amahagane are sacred jewels which grant the owners godlike powers, such as Kamui. Now, rumors are spreading of new, ungodly creatures fighting with Heishi warriors, even without the powers of Amahagane. Yoshitsune and his companions must draw their weapons again, and with the new strength given to them by the Amahagane, defeat the new evil to save all of Japan.

Genji: Days of the Blade, sequel to the PlayStation 2 game Genji: Dawn of the Samurai, is an action game, based in ancient/feudal Japan, in which you must defeat a new, mysterious source of evil to save your country. You control one of four characters (changeable in real-time), each with their own weapons, abilities, strengths, and weaknesses.

Yoshitsune Minamoto and Benkei Musashibo, the main characters of the previous game, join with Gozen Shizuka and Lord Buson to complete their quest. Yoshitsune is a young warrior who wields a katana in each hand, Benkei is a mighty warrior-monk who uses a war club and a naginata for weapons. Shizuka is a nimble priestess who is adept with chained blades, and Buson is a God of War from the Overworld who carries a double saber and can use supernatural powers.

The game play involves fighting many enemies and bosses with regular attacks, combo attacks, and Kamui. Kamui is a power that you can use to summon a magical space around you in which you unleash multiple special attacks on surrounding enemies by pressing buttons in series as they appear on the screen. Your Kamui bar fills as you land successful hits on opponents. The characters travel through both levels based on real locations in Japan and fantasy locations, defeating everything from regular Heishi warriors to giant, mutated enemy crabs. The level design involves platformer elements and solving small puzzles, such as destroying Masho flowers scattered throughout an area to open a door.

The game also has RPG elements; you collect Amahagane and Mashogane hidden around levels and from fallen enemies. They can be used to augment character stats and weapon attack power, respectively. You can also find new weapons and items such as herbs with healing properties, or scrolls that give you attack bonuses for a period of time.