Marika Katou, a third year student at Hakuho Girls' Academy, is a legitimate space pirate with a Letter of Marque. Between her studies, leading her school's space yacht club, working part time at Cafe Lamp, and being the captain of the space pirate ship Bentenmaru, Marika's days are very busy. One day, Marika gets a job to rob a high-class passenger ship, and she discovers that on the passenger list is Kanata Mugen, a boy who owns a "galaxy pass". Thus, an adventure featuring a hyperspace race between pirates and one young boy begins.
Kaoru is a 17-year-old boy with an SM fetish, secretly dreaming of an SM relationship with his childhood friend Nana. One day Kaoru's mother asks Nana to hide all his SM toys so that he will study for a change. However, Nana finds the leather one-piece that Kaoru bought and tries it on, but she accidentally locks it and does not have the key! This is the beginning of a very strange relationship..
Lucky Star narra a história de um grupo de 4 estudantes, cada uma com uma personalidade única. A personagem principal da trama é Konata Izumi, uma jovem atlética e inteligente que apesar disso, é muito preguiçosa na escola devido seu amor por animes, videogames e falta de interesse pelos demais. A série passa com as quatro personagens principais em seu primeiro ano da escola secundária.
