Momonga is a flying squirrel with distinct features: beady shiny eyes, long white cheek fur, a distinctive blue shadow on its nose bridge, and a large, blue, fluffy tail. This tail can wrap around its body, and Momonga achieves brief glides when spreading its limbs.

Its personality is hyperactive, self-centered, and attention-seeking. Momonga frequently begs for praise, steals food, and provokes others, though its confrontations rarely escalate physically due to limited strength. A core motivation is a conscious effort to "act cute," leading it to imitate other characters' mannerisms, especially Chiikawa's yawning and crying. Even in danger, Momonga prioritizes requests for food or rest.

Momonga's backstory implies a significant event: being chased by the monster Dekatsuyo, who demanded it "give it back." This encounter suggests Dekatsuyo’s body was stolen via dark magic. Later, Momonga destroys a body-swap slot machine at a game center, stating the act was done "just in case," reinforcing the implication that Dekatsuyo may have taken over Momonga's original form.

It maintains a close friendship with Kani, a crab running a second-hand bookstore. This bond is highlighted when Momonga places a crab headband onto Kani, revealing her design. Kani represents one of Momonga's few consistent positive connections.

In daily life, Momonga discovered an "infinite white rice spring," serving as its primary food source. Its fur thickness also changes based on weather conditions.