Plot summary

The year is 1840. Koshiro has always thought he's just the son of a salmon vendor, but one day he finds out that he's actually the illegitimate son of the local daimyo, and has to take up the position of his dead big brother. The domain has a huge debt, and Koshiro's father, the retired daimyo Ikkosai, wants him to declare bankruptcy to clear the debts – which would also mean a seppuku. Koshiro starts to save up money with the help of his spunky childhood friend Sayu and his two new brothers, the sickly Kisaburo and the half-with Shinjiro. But where has all the money disappeared in the first place?