Grandis is a 28-year-old woman.

She was born into a rich Italian family, but is now broke and disowned by her relatives.

She is the leader of the "Grandis Gang," a trio of jewel thieves.

After being rescued along with Nadia, Jean, and Marie by the Nautilus, she and her henchmen befriend the children. She develops a huge crush on Capt. Nemo. She also becomes a mother-figure to Nadia.