Bigga is a young woman encountered by the protagonists Echika Hieda and Harold W. Lucraft during the course of a past investigation. She is established to be eighteen years old. Bigga is recognized as a highly talented bio-hacker, possessing advanced skills that interface with the technological systems of her world. This expertise allows her to perform complex technical procedures, such as attempting to enhance a person's data processing powers through risky bio-hacking methods.

Bigga harbors special feelings for Harold W. Lucraft. These emotions influence her motivations and actions, placing her in a complex position relative to the main pair of investigators. Her role in the story is primarily one of support, particularly for Echika. During moments of emotional crisis, Bigga provides crucial personal support, such as when Echika struggled with difficult truths about her partner. On a professional level, Bigga applies her bio-hacking abilities to assist Echika, notably when the investigator lost her data processing capabilities, attempting a direct technological intervention to restore them. Her skills are also applied in active investigations; she uses deductive reasoning involving art history to help narrow down a suspect's location during a kidnapping case. As the narrative progresses, Bigga shifts from a character introduced in a past context to a more active participant in current events, directly influencing the capabilities and relationships of the main characters. Her key relationships are with the two leads: a supportive friendship with Echika and a one-sided romantic interest in Harold.