Cumulo is a giant cloud humanoid, with a chubby & curvy nude female body. Her soft white form has a large belly, an enormous bust, thick hips & thighs, pudgy limbs and a sizeable rear end. Her eyes are simple black "circles", without pupils or irises. 
Cumulo is shy and friendly, for the most part, though she is easily flustered. Due to her being a cloud, she passively absorbs water particles & ice crystals from the atmosphere, which may cause her to grow bigger and change unpredictably.