Tetsu no Michi

Akiretasu is a skilled swordsman who gains fame in the Roman Colosseum. Boastful about his strength and status, he catches wind of rumors of a boy far stronger than him—one who slew seven tigers who hails from Japan. The boy, Takeru, happens to be journeying to Rome with a caravan of silk merchants. Akiretasu is intrigued, and sets out to meet him. Both take the same path—the road connecting East and West, the Silk Road!

(Source: MangaDex)

Included one-shot: 0-jigen no Oka