Nazca : Blades of Fate (Vol. 1) Episodes 1-3

At a kendo match, 17-year-old high school student Kyoji is stunned when Tate, his coach, momentarily transforms into an exotically armoured warrior. Over the next few days, Tate behaves erratically, alarming his students and his fiancée, Yuka. Kyoji discovers he, Tate, and their friends are the reincarnated spirits of Inca warriors. But Kyoji is Bilka and Tate is Yawaru enemies in a blood feud dating back to the Spanish conquest of Peru. Yuka and Kyoji travel to South America, hoping to find the missing Tate and figure out what's going on. Their visit leads to more flashback episodes.