Mondo's genius girlfriend, whose intentions match Mondo's. Her main color is green, matching the eyes of the Saint Star Dragon like Mondo's red matches it's gem. Upon entering the Sixgate world she was granted the ability to "see into the hearts of monsters" allowing her to telepathically communicate with the monsters without language. Rokuna's combat strength is in effect and field spells, otherwise she battles using an indefinitely extending pink ribbon that functions much like a tentacle.

She loves cute and sparkly things, takes care of the house hold and has an affinity for pink; she'd be the perfect girl if not for her interest in physics, creepy tendencies and world shatteringly bad cooking. Those that known her well are afraid of her, her classmates but especially Mondo and her father. Rokuna is prone to violent retaliation if either does something she considers rude, ranging from stomping to kicking in the face to smiting with lightning. The latter especially applies when Mondo is hitting on other girls. She holds no hard feelings to the girls themselves though.

Rokuna is fairly motherly in nature, gladly taking care of things that need it, whether they be cute little things or gigantic monsters. Having grown up without a proper mother figure and needing to take care of her childish father, she drifts between being either dependent or assertive in her role. On one side she can stand strong and takes responsibilities, yet when Mondo's around to offer protection she gladly takes it. Their "romantic" interaction's almost like an act from a Shojo manga, love bubbles included, except with the addition of spectators being weirded out by it. When it comes down to it though, she'll save both herself and Mondo from the dragon.