Raiden Bosenmori Mei, going by the name "Acheron",  is a lone drifter, who claims to be a Galaxy Ranger, but is actually the Emanator of Nihility and a Self-Annihilator in Honkai: Star Rail. Aloof, stoic and taciturn, jaded and world-weary, Acheron is highly nihilistic, to the point where she is hardly able to feel anymore. She also is gradually losing her memories, and ultimately her existence. In her gloominess, she employs dull flirtation, trying to feel companionship and intimacy once again.