In California's Center City, shy but kindhearted Joseph Carter "Joey" Jones lives with his grandmother, working in a coffee shop. Though his family is financially burdened and he is bullied at school, he remains cheerful. A robotics enthusiast, he wants a top-of-the-line toy robot called a Heybo more than anything. One day Joey and his friend Simon "Psy" Kaina come across a destroyed Heybo discarded by a group of rich kids. He takes it home and repairs it himself, excitedly naming it Heroman. However, one night Heroman is struck by lightning and comes to life, growing several times its size in the process. That same night Center City is attacked by aliens called Skrugg whose attention was brought to Earth after Joey's acquaintance Professor Matthew Denton made attempts to contact them. Along with Joey, Heroman quickly heads to the scene of the attack, where he finds people in trouble, including his friend Lina Davis and her father. Using an arm-mounted controller, Joey is able to command Heroman to use superpowers to fight off the Skrugg and rescue civilians. As the aliens continue their invasion of Earth, the duo are the only ones separating humanity and destruction. [Written by MAL Rewrite]

11-year-old Persia has grown up alongside the animals on the Serengeti plains of Africa. Twins Riki and Gaku Muroi and their grandfather, Gouken, bring Persia to Japan with them, where she will live with a couple (who Persia calls Mama and Papa) that own a grocery store. During the flight to Japan, Persia finds herself in the "Lovely Dream" where she meets the Fairy Queen, who explains that the Lovely Dream is in danger and requests Persia's help. Giving Persia a magical headband (which can also summon a magical baton) that allows her to transform into a teenage girl, connecting her to the Lovely Dream and allowing her to use magic. She is sent with three kappa back into the regular world with the mission of collecting love energy to thaw the frozen Lovely Dream. If Persia fails her task of collecting love energy or if someone catches her using magic, Riki and Gaku will be transformed into women.

Haruki Nakano lives an average high school life, except for the fact that his mother is overseas and he shares an apartment with his four sisters. There's the oldest, Mutsuki, who has a bad habit of falling asleep in his bed, the junior high school student Yayoi, who hits him whenever something happens, and then the grade school twins, Uzuki and Satsuki, who love to play pranks on their older brother. Stuck in a house with four girls, Haruki has to deal with all sorts of trials. From going grocery shopping, watching scary movies, to kissing practice, life is never boring in Danchigai!