Lucy Morgenroth and Leander von Cherub get along well with each other - if Lucy is not doing her favorite sport, parkour. Since Leander's job, as her invisible guardian, is to protect Lucy without her noticing it. Not an easy task with a girl who would rather balance on the railing than sit at home or practice ballet. At some point, Leander decides he's had enough. He goes on strike - and has no idea that his problems are just beginning.