The new shonen action manga from the creator of Magi is here! Musashi is a teenager living under demon rule. As children, he and his best friend made a promise: to become the greatest warriors in the world and overthrow the demons. But life intervenes, and five years later, he finds himself about to become a miner. Yet can Musashi truly be satisfied with a "normal" life? At age 10, best friends Musashi and Kojiro sat in excited silence as Kojiro's father spun tales of evil demons who preyed on the innocent, and the warriors who defeated them. Practicing swordplay, the two swear an oath to become the strongest in the world and But as they grow up, Kojiro turns cycnical, and Musashi comes to realize that he can't turn back 150 years of demon rule on his own. He's being called a prodigy with a pickaxe, and he's almost ready to settle for a life of labor. Yet he can't shake the feeling that he still has a responsibility to act... and, soon, the injustices of his world will force his hand...

"I will defeat... all the Demon Gods!!" Musashi and Kojiro have set out on their quest to eradicate the demons in the land of Hinomoto. However, just when they expected to seize their first victory against the Demon God "Hellfire Tengu," it was defeated instead by the captain of the Takeda Band of Bushi, Naotora Takeda. That frustration lights a fire under Musashi, as he and Kojiro set out to find the next Demon God, and begin their quest for "Unity Under Heaven!"

After escaping the clutches of allies turned rivals, this burgeoning Band of Samurai gets some much-needed aid and wisdom from a new member, the experienced samurai Tsugumi. But they’re going to need more than an extra set of hands to achieve their new goal—taking on a demon god on their own…

鬼神に対抗できる唯一の武器、鬼鉄刀。“刀の試し”を突破し、鬼鉄刀に選ばれた者だけが、武士として鬼神との戦いに身を投じることができる。しかし、“刀の試し”を受ける武蔵の身に異変が起きた。武蔵に宿る謎の影が、魂を黒い鉱石へと染め上げる。影は武蔵の脳裏に過去の記憶を映し出し、武蔵は心の奥底にしまった幼少期の記憶と向き合うことに──。

At the Daitou Mine, the mysterious swordsman Shirou Inukai is attacking Kojiro and Tsugumi. Inukai has a single objective: "to steal katanas." Musashi has come running back after escaping the trap he fell into, but the three of them seem helpless against Inukai's strange power...However, the obsidian power slumbering within Musashi has awakened, and the Kanemaki Band's counterattack starts now!

次なる舞台は上杉武士団が拠点を構える「播磨国」。淡路島に巣食う最大規模の鬼神を討伐すべく団長・上杉竜臣は大規模軍勢を配備。武蔵たち鐘巻武士団も天下分け目の大戦へと巻き込まれていく……。覚悟と絆が試される“淡路島奪還作戦編”、開幕！！

“淡路島奪還作戦”に参加することになった鐘巻武士団。しかし、武蔵一人だけが別の小隊に配属されてしまった。そこで武蔵が出会ったのは同年代の若年兵たち。武蔵が曲者揃いの彼らを観察していると早速事件が勃発、“誰が一番強いのか”を決めるべく大乱闘が発生する！　自分の剣技を試すため、武蔵も参戦を決意！　武蔵vs.島津vs.尼子、小隊長の座を懸け、火花が散る！！

淡路島奪還作戦に参加することとなった鐘巻武士団。最終決戦を前に武蔵の弱点が浮き彫りとなった。仲間と刀気を繋げない武士に価値はないと知った武蔵は、尼子と共に修行に励む。みちるも修行に加わり光明が見えてきた矢先、武蔵とみちるの黒曜の力が暴走し緊急事態発生！ みちる出生の秘密が明らかとなり、物語は核心へと動き出す！！

決戦前夜、四郎・静六の急襲で、主要戦力は戦闘不能となり上杉陣営は壊滅寸前……。淡路島奪還作戦に暗雲が立ち込める。上杉武士団、勝利の鍵は、「黒子の軍略」と「黒曜の女神の覚醒」！　淡路島奪還作戦は最終局面へ！！！！

黒子が静六との軍師対決に勝利し、直江が静六の鬼鉄刀を粉砕。刀気を封じられていた精鋭・黒服隊も復活し淡路島奪還作戦は最終局面へ。直江vs.静六、尚虎vs.四郎、武蔵vs.八咫郎──。日ノ本の未来を懸け戦いはさらに激化する！！