Ep 13. Viper? I Hardly Knew Her!

Sgt. Frog season 1 episode 13, titled "Viper? I Hardly Knew Her!" opens with a new intergalactic enemy named Viper. Viper is a snake-like creature with the power to make anyone his ally by hypnotizing them. His next target is the Hinata household and Fuyuki is the first one to be hypnotized. However, the hypnosis doesn't work on Natsumi, who quickly realizes that Fuyuki is acting strange.

Natsumi investigates and finds out about Viper's plan to take over the world. She then decides to take matters into her own hands and confronts Viper. However, Viper manages to hypnotize her as well. Meanwhile, Keroro and the rest of the invasion force have completely fallen for Viper's hypnosis and are now doing his bidding.

The situation seems hopeless until Tamama comes up with the idea to use a special gadget to defeat Viper. The gadget releases a high-pitched sound that breaks the hypnosis spell. Tamama manages to use the gadget on Natsumi and Fuyuki, and they snap out of the hypnotic trance.

Together, Natsumi, Fuyuki, and Tamama team up to take down Viper. They manage to locate his hiding spot and engage him in battle. Viper uses his hypnotic powers to control the invasion force and turn them against Natsumi, Fuyuki, and Tamama. However, with the help of the gadget, they are able to break the hypnosis and defeat Viper.

In the end, the Hinata household returns to normal, and Keroro and his invasion force are once again foiled. However, there is a hint of a new enemy on the horizon, leaving the show's future in a state of uncertainty.

Overall, "Viper? I Hardly Knew Her!" is an action-packed episode full of humor, drama, and suspense. It exemplifies the show's trademark blend of sci-fi and comedy, making it a must-watch for fans of the series.