Shouwaru Boukun Kishu to Nagasare Senba

A thirty-year-old Japanese male is teleported to Japan's warring-era. But instead of being reincarnated as a samurai or ninja, he is now a pony! Cute and spry, he is enjoying is carefree new life but all that changes when he runs into a human who is fighting off a bear attack! The pony dashes and rescues the man, and thus begins his new life...as a warhorse!

(Source: KUMA)

Note: Includes a bonus chapter.