In Mahou Shoujo Lyrical Nanoha, Nanoha Takamachi is a sweet if naive third-grader. However she has always felt like she is missing something in her life: all the people around her have someone their are very close to but she lacks this. However, Nanoha is no longer an "ordinary" third grader when she meets and helps the wounded ferret, who just happens to be a mage from another planet, Yuuno Scrya. He has come to Earth to gather the "Jewel Seeds," mysterious artifacts containing great power. Nanoha agrees to help him, but the task seems harder than presented when she meets Fate Testarossa, another girl searching for the Jewel Seeds.
In A's, six months after the first season, Nanoha still remains in contact with her best friend Fate. However, things take an unexpected turn when she is assaulted by a special "Belka" type mage, Vita of the Wolkenritter. Just in time to save her comes Fate, but Vita also has backup. The group of the four, the Wolkenritter, are seeking mage's "Linker Cores" for an unknown purpose and manage to steal Nanoha's.
Ten years after A's, in StrikerS, Nanoha is a commander who trains new mages. She takes in two fresh recruits to pay special attention to, Subaru Nakajima, who idolizes her, and Teana Lanster, Subaru's best friend. Nanoha is an S ranked mage and is still great friends with Fate and Hayate.