Koukoku no Hiiro

Kotetsu Miyasaka is a kendo prodigy. While his twin brother, Yayoi, practices the sport, though, he lacks his sibling's skill, enrolling in a different school to try and differentiate himself. When things go wrong at Yayoi's new school, though, Kotetsu finds himself caught up in a potentially life-or-death confrontation -- only to suddenly find himself swept back to Edo period Japan where the stakes are infinitely higher!Taking in by Souzou Sagara and his roshi band of samurai, Kotetsu must find a way to survive in the past and possibly help shape Japan's future!

(Source: Yen Press)