However, here are a few possibilities based on your description:
* You might be thinking of a specific character from an anime: It's possible the frog you remember is a minor character in a larger anime. Could you recall any details about the anime, like the main character, the setting, or the general plot? This would help pinpoint a specific anime.
* You might be thinking of a manga: There are a number of manga series that feature anthropomorphic characters, including animals. It's possible the frog you remember is from a manga that hasn't been adapted into anime yet.
* You might be thinking of a video game or other media: Alien frogs could appear in a variety of media, not just anime. If you can recall any other details about the frog or the story it was in, it may help you identify the source.
Please provide more details about the anime or the frog you're thinking of, and I might be able to help you find the title!