Sorry the manga is called Furi Kuri
Well basically it is just about an alien that had gotten into this boys life because her vaspa...that if you are chosen to be "the one" will have these "creatures" of some sort grow out of your head...well it accidentally ran over him..and even though she did not believe it at first....he would be "the one" that could help her become stronger to find this other aliens that was captured...
This other alien is her enemy yet it is...as explained in the show her "love"
Well these other people are hunting after her are trying to make the boy betray the alien...of which he is helping....but he refuses which coses them to catch her by hand...well while all of this is happening...weird things...because of the alien and the boy who's head is holding these creatures that come out at a certain time....the city is becoming a strange place to live at...well the alien in the end just wanted this power....that came from this guitar....all to herself and ends up fighting the boy who ends up with the power...but the boy refuses to fight her because in end her ends up liking her...so she offers that he could come along but then changes her mind because he is so young...so they return to their normal lives..like nothing ever happened...
So basically the alien just was searching for this hidden power that can only be reached by someone who is chosen like the boy...
As for your question encryptedenigma-san...if you watch the anime closly they will say what "Fooly Cooly" means.
I love FLCL its my Favorite anime ever and imo the best thing ever made
I dont think FLCL is even THAT confusing either.Sure its absolutely crazy but when you read between the lines you see its a story about a kid thats growing up to fast[Trying to hard too] surrounded by people with major problems and stuck as a child in his brothers shadow with no real "identity" of his own in a life of bland mediocrity.You can almost ignore all the robots medical mechanica aliens and dimension portals and just look how the various characters deal with some fairly realistic social/mental problems that are only brought to light by crazy happenings
c/ped this from another topic but it still stands.I actually just watched it all again today in one sitting and its just as cool as ever 😄