If you're looking for manga similar to Kaeru no Pickles: Kimochi no Iro, you might like these titles.
"There’s an old man with a face like a frog living in my house…what’s up with that?" A short comedy about what happens when an elementary school student who looks good in short pants and a middle-aged amphibian live together!
One day a frog saves the life of a bad witch. The witch promises to grant one of the frog's wishes... Which is to turn into a beautiful girl! Will our Frog-chan fulfill her dream and fall in love?
Mimori is the princess of the frog kingdom, a fantastical place populated by the human frog tribe and, well... frogs. One day a young boy named Aoi shows up on the borders of the kingdom, claiming that his elder brother Makaeru cast a spell on him that causes him to transform into a frog when splashed with water. Together, Mimori and Aoi set out on a journey to find a spell to cure him.
Kokoro found a strange machine in her basement, as well as a variety of problems to solve!
In the year 2020 it became possible to travel to the "electric monster world" using special portable telephones. Making friends and sharing telephone numbers with the "electric monsters" became popular among humans. Our protagonist, Shigeki, is one such person. Although he originally arrived in the electric monster world on accident, he became determined to travel the world with his new electric monster companion Kuribute, and make more new friends while he was there.