Holy crap I can't believe this. I figured out what Hikaru and Kaoru's names mean! They're a reference to
Castor and Pollux in Greek Mythology!
Compare:
Hikaru means "shining"
Kaoru means "sweet smelling"
Castor means "shining"
Pollux means "very sweet"
That can't be a coincidence.
EDIT: whoops. Messed up one of the names there.