Kaeru No Utaga
Let's learn the song!
Arigato, Michael!
Let's sing the song as a round! Arigato, Rana and Michael!
Additional information (translated by Rana Harada):
The origin of Kaeru no Uta came from a 19th-century German song, Froschgesang (see below). Okamoto learned this song from a German composer, Dr. Heinz Werner Zimmermann, who visited Japan around the 1930s. Okamoto wrote the lyrics to the song, and it is known as Kaeru no Uta today. Kaeru no utaga is a popular song that is commonly found in Japanese music textbooks.
Source: https://www.tamagawa.jp/social/useful/tamagawa_trivia/tamagawa_trivia-22.html