Seeme is a Somnium, a life form of superior capabilities serving as Lamia's constant companion. She typically manifests as a large yellow moth or bird-like creature capable of sustained flight and long-distance travel. Her large red eyes provide comprehensive vision in all light conditions, aiding her scouting activities. This form represents a deliberate reduction from her original power state, chosen specifically to accompany Lamia after he left the Somnium homeland; her original body resembles Betterman Lume.

Beyond this primary appearance, Seeme can adopt a larger, four-legged form. In critical situations requiring greater power, she consumes fragments of a specific seed originating from Hinoki Sai's mother, triggering a metamorphosis into Betterman Lume. In this evolved state, she manifests as a glowing figure with a luminous yellow hue, dark blonde hair matching Lamia's length, and an opaque dress distinct from his scaled hair structure. This transformation grants access to significantly enhanced abilities suited to dire threats.

Seeme's actions stem from a profound love for Lamia. This devotion compels her to maintain her weaker, travel-conducive form to remain by his side despite his typically reserved nature. Demonstrating proactive loyalty, she secured the vital Vivele Fruit from Mario Sai's body in India to preserve Lamia, directly enabling his inherited memories and physical connection to Hinoki Sai. Her presence consistently accompanies Lamia's interventions when human protagonists face peril, and she shares his ultimate objective of confronting the entity Kankel to protect Earth's life.