A young high school couple out on a date saw what looked like a falling meteorite, and inside, they discovered a little baby girl! The two of them married and adopted the girl, who they named Morumo, as their own. The only problem with this feel-good story is that now, as a high school freshman, Morumo is 16.4 meters tall!

Morumo still has a pretty happy life. She's popular with locals and tourists alike, and she goes to school everyday with her childhood friend Miharu. Then one day, a mad scientist, who specializes in experimenting on young ladies, injects Morumo with a serum that reduces her to 1/10 of her normal size. Her weight remains the same, so she is super-dense and tough like a superhero. Suddenly, it seems like all the joys of an ordinary life are within her grasp!! Sadly, the serum's effects are temporary and soon Morumo returns to her giant state.

But now that she knows a normal life is possible, Morumo is not going to give up! Even if it means she and Miharu have to allow a mad scientist to experiment on her, surely the ends will be worth the means!