Ruiko Saten is a friendly and energetic middle school student from the anime series 'Toaru Kagaku no Railgun'. She is a Level 0 esper, meaning she has no measurable supernatural abilities. Despite this, Ruiko is an optimistic and supportive friend, often seen with her best friend, Uiharu Kazari. Her curiosity and adventurous spirit sometimes lead her into dangerous situations, but her loyalty and bravery shine through in her efforts to help her friends. Ruiko's role in the series highlights themes of friendship and the value of non-superpowered individuals in a world dominated by espers.