Her voicebanks' names of "Sugar" and "Spicy", as well as her age of 11, are likely a reference to the old nursery rhyme What Are Little Boys Made Of?. In the rhyme, little girls are said to be made of 3 things, 2 of which are "Sugar" and "Spice".
Her hat is eel themed. The website words it as "Hat: Ataman Hat (Eel)" referencing the Russian "Ataman style" written in Japanese as "Otaman" (オタマン) of which the hat resembles. As shown in promotional art, its expression changes often matching or complimenting Una's expressions.
Her attire in her Sugar art is based on a marching band outfit, while her outfit in her Spicy art is based on a Japanese school uniform.