What is Sgt. frog?

Sgt. Frog, or Keroro Gunso in the original Japanese, is a humorous manga about a brother and a sister who come upon a froglike alien who was hiding inside the brother's bedroom. The brother is and occult fanatic and the sister is like the "golden child," with the perfect grades, figure, and sports ability. The mother of these two children is a manga editor, and she absolutely adores Keroro, the frog alien. It's pretty much about how that frog and its comrades try to invade Earth while their hosts, the children and mother from before, are housing them and trying to keep them from succeeding. It's also just a bunch of random, hysterical nonsense condensed into a graphic novel.