Wagemon: Nagasaki Tsuyaku Ibun

Nagasaki became an international city during the Edo period with many Westerners coming back and forth for trades. The interpreters were a group of professionals needed for negotiations as well as to gather information.
In the 2nd year of Kaei (1849), a young man called Ijima Sota arrived at Nagasaki from Edo to pursue the mystery of his father's disappearance. Sota, who has a great sense of curiosity, was studying English at a cram school and accidentally came across a secret of his father. He, with the help of his friends, decided to come with a plan to find out the truth.
(Source: DramaWiki)