Magno Vivian is the commander of the pirates and everyone addresses her 'Boss'. She is one of the first-generation colonists from Earth that was onboard the Ikazuchi colony ship, hoping to populate other planets around the galaxy. She is over a hundred years old and is filled to the brim with knowledge and wisdom, most of which reflects the same kind of wisdom that can be applied to both genders, before their separation into Mejare and Taraak. She often hands out pieces of advices and directs the crew in their duties.
Also, though not directly stated, she may be Hibiki Tokai's sister. This can be derived from the picture she has of herself when on the colonization ship holding the infant Hibiki. However, it can be argued that this may not be true, as stated by Hibiki's "grandfather" (in reality, he is Hibiki's uncle) during a conversion near the end of the second season, that he remembers Magno always coming to play with the infant Hibiki on the colony ship. As such, she may merely be an age-old friend of his, during her days as a youth. She is voiced by Hisako Kyouda in the Japanese dub and Katherine "Teng" Perez Masilungan in the Filipino dub. (Source: Wikipedia)
It appears that Magno has some sort of heart condition, as she is seen clutching her chest in pain on occasion, though she keeps the knowledge of her condition secret. Whenever talking to Hibiki, she calls him"little one" instead of his name. Throughout the series, Magno becomes a sort of mother figure to Bart, as evidenced by their conversations and what took place on the diseased planet.