Gemma is a middle-aged man of average build and height. His face is wrinkled with old age and the bags beneath his eyes are made prominent. His cheekbones are defined by the wrinkles, with his cheeks taking a shallow, inward curve. In addition, Gemma has a very prominent chin. He has short, partially spiky dark hair, with fringes running above his creased forehead. He has thick, dark eyebrows, and very, very small dark eyes. He has a striking resemblance to his deceased father, Botohn.
He dons a pleated, button-up shirt depicted pastel green in the anime, which he matches with a pair of dark pants and shoes. Finally, Gemma keeps a gun hidden somewhere in his person.
Gemma is a lighthearted fellow with a good sense of humor. He seems to find even the littlest things hilarious, and can laugh for a great period of time. In spite of this, Gemma has a serious side to him, and is careful when mentioning sensitive topics to people.
When Haru Glory introduces "Shabutarō" to Gemma, he breaks out in hysterics and greatly annoys the lad. When he sobers, Gemma offers to discuss about Haru's parents, his mother, Sakura Glory, and his father, Gale Glory. The subject of his father agitates Haru deeply. Gemma stirs the conversation away and praises Haru's fighting skills, claiming that Haru is the best on the island, before laughing over "Shabutaro" once more. As they converse pleasantly, an old man enters the shop and mistakes Gemma for his late father, Botohn. Haru and Gemma quickly disprove this, and Gemma offers the man a cup of coffee. The old man eventually heads off.
Later on, when Haru runs away from Cattleya Glory's emotional outburst and confides with Gemma, the latter is once again hysterical over Haru's apparent heroic destiny. But when Haru asks about the Rave stone, Gemma pauses for a beat, laughs again, and finally reassures Haru that Cattleya is merely concerned for his well-being. When Haru leaves, Gemma notices a mysterious figure stalking towards his shop.
Days later, Gemma welcomes into his shop a stranger who seeks the Rave stone, and knows his name as well. When the man refers to him as Gale's friend and inadvertently displays his Dark Bring, Gemma levels a gun at his head and exclaims that the Rave stone is not in the island. Before the man leaves, he beats, shoots, and leaves Gemma crippled and bleeding.
After Haru finds him, Gemma attempts to reveal the truth about Gale to Haru, only to cough out blood instead. He is saved by Plue from bleeding to death, to the point where he could sit properly without straining himself.  Later on, Haru, Cattleya, and Shiba, the elderly from earlier, gather in Cafe Tsubomi as the oldest man recuperate. When Haru demands the truth about their father, Cattleya is unable to answer. Instead, Gemma takes it upon himself to explain Gale's circumstances. He reveals that 15 years ago, Haru's father disappeared from the island to search for the missing Rave stones. It was around that time that the Dark Brings appeared on the island, and Gale journeyed to find the only power that could stop them. Gemma assures Haru, however, that Gale had not once abandoned his family. Later on, when Haru finally pursues his destiny as the second Rave Master, Gemma stands behind Shiba as the latter reads Haru's letter to him.
- (To Haru Glory) Maybe she thought you would leave and never come back? In other words, she doesn't want you to leave. After all, you're her only family.
- (To Haru Glory) Gale is just like you. He can never betray his family.