Second TV (flash animated) series of Keroro Gunsou.

Aoi, a regular boy, is cursed with a spell that turns him into a frog whenever he gets wet. He is sent to another world with a frog kingdom to find the princess to undo the spell. When he finds out that she doesn't know how to lift the curse, they set out to find the spell that will. Along the way they meet many interesting creatures, come across many dangers, and make many new friends. (Source: ANN)

Pet shop owner's daughter Chika Tokorozawa spends every waking hour with her dog, Rin Tin Tin, who repays her love by watching over her while she sleeps. Based on the manga in Young Sunday magazine by Maki Otsubo, who is better known in the manga world for Mr. Cinema. (Source: Anime Vice)

During a vacation Natsumi is visited by a female alien and male alien who she later gains feelings for from the ocean that makes her the Deep Sea Princess who, along with the rest of the Keroro Platoon, encounter many dangers summoned by a mysterious creature. (Source: Wikipedia)