Assuming the form of a young man, Biran briefly challenged Zain after insulting him and his Zu. Biran later first made himself known to Kuuga when he attacks Zain for "stealing his turn". Once his turn began, Biran gets to kill off 180 people within a period of 2 days by attacking any form of water transportation and slaughtering the passengers single handily.
But he is driven out of his game by the smell of blood overriding his senses, the police arrive to fight Biran until Kuuga arrives to fight him. But when Mighty and Titan Forms have no effect on the Me Gurongi, Biran is forced away when hit with a modified bullet. In spite of being injured, Biran was intending to make his quota to the very end.
When Ichijo manages to lure Biran out into the open, Kuuga kills him in Dragon Form by using the Splash Dragon.
Kamen Rider Decade
A piranha monster that is one of the leading Gurongi overseeing Gamio's revival. He is destroyed by Kuuga's Mighty Kick when he attempts to intervene in the battle between Kuuga and Decade.