To be mentioned, Lulu appears on-screen after Celina and even Rin. According to Leo Akaba, Lulu is crucial to his plans.
Apart from her pink eyes, Lulu's face resembles those of her counterparts. She has long, dark purple hair which extends past her lower back even when tied up in a bow-shaped style and has shorter, lilac side tails. She secures her hair with a wing-shaped barrette and, after the invasion, dons large, feather earrings. Lulu is the only one between her counterparts with longer hair and side tails. Like her counterparts, she also wears a bracelet.
Before the Invasion of the Xyz Dimension, Lulu dressed simply in a yellow and white, knee-length dress with white shoes. After the establishment of the Resistance, however, she wears more practical clothing. A cream vest with an under dress that splits into three, worn out pants, brown boots, two brown belts, and a red sash that evokes Yuto and Shay's scarves is worn on her right hip.
According to Yuto, Lulu is kind and loyal to her friends, fighting for the sake of their homeland together with their Resistance comrades. Yuto commented that Zuzu's desire to protect her friends is similar to Lulu. Due to the invasion by Duel Academy, Yuto stated that Lulu would never learn the Summoning method used by Fusion users, suggesting that like Yuto and Shay, Lulu developed resentment for Fusion Summoning. She is also shown to be brave and confident, challenging Yuri to a Duel when she was cornered by him. Like Yuya Sakaki, Yusho Sakaki and Yuto, she believes that Dueling is not a tool for conflicts but instead for the sake of making people happy and smile.
'Ruri' is a feminine Japanese name and, depending on the Kanji used, it can mean: (流理) 'flow or logic', (留莉) 'detain or jasmine', or simply 'emerald'. For this Kanji, Lulu's Japanese name means (瑠璃) 'lapis lazuli' - a gemstone that is a deep blue and is greatly prized for its unique, intense colour. Ancient traditions in Japan believed that babies who were named after gemstones were protected from harms of evil spirits. Her family name can be read by separating the two syllables apart. (黒) 'Kuro' means 'black' and (咲) 'Saki' means 'bloom'.
Her international name rhymes with 'Zuzu', one of the three counterparts she resembles, which means 'pearl', 'calm', 'peaceful', or 'protected' - the latter reflecting to her Japanese name. It is also commonly used as a pet name. Her last name, 'Obsidian', refers to a black, volcanic glass.