Udono is Gennosuke's portly and jovial best friend. Altough he is very friendly, he faces massive rejection from the ladies. Often coming across as abrasive, he speaks his mind, and is unabashedly honest.  Udono's redeeming quality is his ability to expand and contract like a balloon. Because of his rubbery nature, weapons bounce right off of him. But unfortunately for Udono his trusting nature opens him to sneakier, underhanded attacks, which could ultimately lead to his doom.  

(Source: FUNimation's Official Basilisk Website)

The heirs to the Kouga and Iga ninja clans, Gennosuke and Oboro, hoped the unsteady truce between their tribes would last—but fate denies the lovers, thrusting their people into war after centuries of peace. The terms are set on two scrolls. One bears a list of Kouga warriors. The other holds a list of those who fight for Iga. The names found on these scrolls can only be crossed out in blood. 

(Source: Crunchyroll)

The Iga clan and the Kouga clan have been sworn enemies for more than four hundred years. Only the Hanzo Hattori truce has kept the two families from all-out war. Now, under the order of Shogun Ieyasu Tokugawa, the truce has finally been dissolved. Ten ninja from each clan must fight to the death in order to determine who will be the next Tokugawa Shogun. The surviving clan will rule for the next thousand years. 
But not all the clan members are in agreement. Oboro of the Iga clan and Gennosuke of the Kouga clan have fallen deeply in love. Now these star-crossed lovers have been pitted against each other. Can their romance conquer a centuries-old rivalry? Or is their love destined to end in death? 
(Source: Del Rey)

Josuke Udono