Maken-Ki! currently has two seasons. The first season adapts the first five volumes of the manga (Welcome to Tenbi, Life at Tenbi and Clash With Venus arcs), while the second season features completely original, self-contained story arcs.
The anime differs quite a lot from the manga, mostly within the Clash with Venus arc; rather than fighting with Venus to rescue Kodama, Haruko is kidnapped directly by Kamigami and rescued by Venus, with the battle is settled between Takeru and an new original character, Kikyo Yamato.
The opening theme of Season 1 is "Fly Away" by Mizuki Togashi, and the ending theme is "Baby! Baby!" by Iori Nomizu & Noriko Shitaya.