Gunfire Samurai: The Mikasa Yamakazi Chronicles (Book 1)

Only the lost magic of the Greegarian Omen can save his land, but this means Mikasa Yamakazi must've executed a thousand samurai in battle just to summon the Goddess in the first place.  The Unbound Samurai of old clashed with the Haduat and routed armies, liberating mankind from the Saduats before fading into legend. Now, with the land again teetering on the brink of a cataclysm, the power of a special sword, The Broken Sword of the Daudane, graces the hands of a worthy Mikasa and with his gangly misfits, they must prove themselves worthy.  Without a master to guide him, he must rely on the lessons of an enigmatic Spirit of Adversity, a mysterious Goddess of Solitude, his team of two special imperial agents, and a banished Wizaryan sorcerer to rediscover the truth of the Greegarian Omen and bring it to light; thus becoming the first champion to do so. Yet doing so means taking dire risks...  Because invoking a Greegarian Omen can kill you.