Mole is the son of Oliver.

After hearing how Gin had been captured by Hougen, Mole digs his way into the prison to free Gin only to hear the leader's refusal. He gets attacked by some of Hougen's minions and, before passing out, he reaches a road where he's found and healed by some humans. Gin had told him about his son, Weed, and so, Mole runs to Ohu searching for Weed, finding Tesshin intead, who brings him to the leader's son. Together, they plan a way to free Gin and, when Mole goes again to the prison to tel the Akita the plan, he finds that Gin's gone. He gets back to Weed and join his army, hoping to free Gin. 

He is not seen anymore after the Hougen Arc and his current status is unknown.

Mole was supposed to appear in Ginga Densetsu Weed anime. His own character sheet can be purchased as official anime production merchandise:

It's unknown why producers decided to cut Mole out of the anime.