Haruko Haruhara is Mabase's newest resident, and an extraterrestrial investigator for the Galactic Space Police Brotherhood.

Haruko is an energetic, spontaneous girl with light-pinkish hair. She claims to be 19 years old, but it is impossible to know if that is true. In the first episode, she runs over Naota with her Vespa and hits him in the head with her guitar. Shortly after, she becomes the Nandaba household's house-maid while working to find Atomsk, the most powerful space pirate in the galaxy.

She has a tendency to switch between a variety of different dispositions to others on a dime, making her difficult to read and unpredictable. She can be very persuasive and stand-offish sometimes to get what she wants. When around the Nandaba men, she is often either promiscuous or found in suggestive situations. She can also act like a mom, a lover or a maid depending upon her mood.

She leaves Earth in the final episode of FLCL, but returns as a teacher in Mabase in FLCL Progressive. In FLCL Alternative, she's back on Earth again tackling a whole host of new Medical Mechanica problems.