Momotaro is a pretentious, old fashioned samurai spirit, who's travelling with three animal companions.
In the beginning, Momotaro is shown to be very prideful of his past acomplishments as a human and he becomes easily angered if he is insulted. However, when Hoozuki changes him from an unemployed punk to a hardworking man, Momotaro becomes much more docile and ears a status in the series as the straight man.
(Source: Hoozuki no Reitetsu Wikia)
