Kuroshoin no Rokubei

In 1868, negotiations between the shogunate and the new government results in the decision to surrender Edo Castle. As the advance party to ensure the surrender of the castle progresses without a hitch, Kakurai Hayato , a timid, low-ranking warrior of Owari who is on the side of the government forces, enters to inspect the castle. However, there is just one problem. There is a retainer of the shogun who refuses to budge. His name is Matooya Rokubei. He was a member of the guards under the direct control of the shogun. Rokubei silently sits on his heels and moves only to relieve himself. Disputes in the castle are strictly forbidden because of a promise to Saigo Takamori and Katsu Kaishu. So Rokubei cannot be evicted by force. Kakurai learns that this Rokubei is impersonating the real Rokubei. They get increasingly confused. However, Kakurai begins to feel a perplexing empathy for Rokubei who stands with traditional dignity, after spending some time with him.
(Source: jdramas.wordpress)
~~Adapted from Asada Jiro's (浅田次郎) novel