Ryukyu Buccaneer

When it's your livelihood on the line, you've got to be willing to do anything to get your hands on the treasure! It is the twilight of the shogunate in Japan, the Bakumatsu, a time of tumult in which ruffians from all walks of life vie for supremacy. Hanagusuku Muta, a Ryukyuan boy from a disgraced clan of nobles, now lives in poverty, stealing just to survive. But one day, he hears rumors of a massive cache of treasure left by a legendary pirate on a small island in the kingdom, one valuable enough to throw all of Japan into disarray. After getting framed for a crime he didn't commit by a group of Satsuma samurai, Muta gets dragged into the vigorous, bloody struggle for the treasure...

(Source: Ichijinsha, translated)