Sgt. Frog , Vol. 19: Karaoke, Cows, and Cleaning?

Keroro and his friends are full of schemes to conquer the Earth, from training soldiers through karaoke to exploiting human reliance on cows to creating the perfect invasion environment with rain dolls! Will these frogs finally finish their fantastic plans? Not if the Hinata family can help it! Are Natsumi and Fuyuki really safe from the galactic green gang?