Lenny is a very kind, calm and polite dog, but also very determined and mentally strong.
She is very loyal for her owners and didn't make a move to stop them as they took away her son, even if it hurt her greatly. She travels a long journey despite being very ill and is ready to fight for her son. She seems to know that she might die soon and thus wants to see that her son is happy before her death comes.
Lenny is shocked and sad to find out that her son seemingly hates her. She refuses to fight her son and tells Weed not to attack him, accepting death and responsibility as a mother. She decides to leave as she saw her son alive and well, but returns when she finds out that he is in bad company.
She shows more stricter side when she sees Mel fighting GB, saying that it's her responsibility as a mother to stop her son from doing bad. She is disappointed as Mel walks in such a company. She is very happy to reunite with her son.
Lenny is a pet dog. She lived with her family in Yokosuka where she gave birth to six puppies just before the end of the year. Five of them were given away within two months, but Mel didn't get a home. They happily lived with each other, but the small yard was a bit crowded with the two dogs. All of a sudden, they got separated by the brother of Lenny's owner.
Weed and GB find her by the river trying to drink. They soon understand that she's very ill. She tells them that she is searching for her son, and Weed agrees to help her. Lenny rushes to Mel's home only to discover that the husky Golvy lives there instead of him. She is told that he has run off by Hook. She hurries up to help her son, as she hears Blue has taken him under his wing. But as she meets her son, he is angered by her breaking the promise that they would always be together, so he attacks his mother, much to Weed's surprise and disgust. Lenny accepts that Mel would rather stick with Blue and leaves him. She goes back to Hook, who tells her that Blue kills pups that disobey him. Weed rushes back to save Mel together with Lenny. They starts a fight, and Lenny tells her son that it's alright for him to kill her. Mel attacks his mother but in the end, he can't kill her, so Blue steps in. As Mel watches Blue hurting his mother, he starts to think of all the happy memories they shared. He attacks his leader to save his mother, but it's clear that he is too weak to fight him. Hook comes to the rescue with a pack of dogs, and fights off Blue and his pack. Lenny is finally reunited with her son, but later on dies from her illness and tells Mel to go and help Weed.