Ririka Katō, alias "Blaster Ririka," is the mother of Marika Kato and widow of Gonzaemon Kato. She possesses blue eyes and long purple hair extending past her shoulders, typically parted slightly on the front-right. Her appearance adapts to her roles: as a pirate, she wore a black coat with gold highlights, red frilled sleeves, a bicorne hat, and a black cape with maroon lining. As an air traffic controller at New Okuhama Airport on the Sea of the Morning Star, she wears a grey trouser suit, white shirt, and red tie. Casually, she favors loose buttoned shirts, trousers, and practical footwear like salmon-colored slippers, often paired with a blue apron featuring a teddy bear design while cooking.

Born in space, Ririka served as a pirate aboard the Bentenmaru, earning her epithet through combat prowess. The novels suggest she may have captained another ship before joining the Bentenmaru. She married Gonzaemon and later left pirating to raise Marika, concealing both Gonzaemon's existence and her own pirate past until Marika's high school years. Ririka intended to reveal this after graduation, but former crewmates Misa Grandwood and Kane McDougal accelerated the plan by announcing Gonzaemon's death. Despite her past, she maintained connections like that with Brigadier General Joshua Quadron of the Tau Ceti forces, enabling her to secure permissions for military training ground use.

Ririka exhibits a strong-willed, exuberant personality balanced by tenderness toward Marika. She provides pragmatic support for her daughter's choices, notably Marika assuming the Bentenmaru captaincy. Her guidance includes a symbolic firearms lesson at a ship graveyard, stressing that pirates wield power responsibly, resolving 90% of conflicts through intimidation. She conveyed that pirates must make autonomous ethical judgments unlike military personnel. Ririka occasionally displays irreverent humor, joking about Gonzaemon's cause of death (food poisoning) and toasting his memory with oversized wine glasses. Her daily life reflects routine domesticity, though she retains habits like consuming sake or wine from glass tankards.

During the Golden Ghost Ship arc, Ririka facilitates meetings between Marika's crew and Princess Gruier Serenity, joining discussions about the ghost ship in New Okuhama's underground district. She later considers career changes while noting the increased romanticism of Marika's piracy. In the film *Abyss of Hyperspace*, Ririka appears during the climax involving the subspace vessel Advaseele. Her arrival, signaled by "Blaster Ririka arriving," provides critical assistance to Marika and Kanata Mugen confronting antagonists seeking Professor Mugen's legacy. This intervention aligns with her pattern of leveraging past expertise to support her daughter's command.