Right Here, Right Now (2006)

Blurb:
Yanase Mizuo was hiding from his tea ceremony lessons in an old temple when a sudden wrinkle in time propels him from the present into the tumultuous world of the past! Lost in an unknown land in an unknown time, he finds help in the feudal lord Takakage. But Takakage isn’t interested in getting Yanase back to the future. Nope! He’s convinced that Yanase is right where he needs to be - in his arms.

Source: www.anisearch.com/manga/1006