Path of the Eternal Sun - The Sentinels Saga, #1

Divided under the sun, United against the darknessFor General Sato, a sentinel of Samas, adherence to the Path comes as naturally as breathing. Honor and duty are the pillars of his life. When a new breed of bandit, more cunning and dangerous than ever before, threatens his home, he finds that all his honor counts for little. The giant known only as Beast, without family or people, is on the brink of achieving his life's work.
He's never known fear or defeat, but an enemy approaches unlike any he has met before. For the first time in his life, Beast will question whether his strength is enough to save him. Young Shin lives contentedly as a cog beneath the notice of the system she serves. When that system finally turns its back on her, she must find the will and courage to survive in a new, terrifying world. Over all, a shadow gathers its forces.
It seeks to engulf Samas, the nation blessed by the eternal sun, in a darkness from which there is no escape.