The lizard Leoi and the turtle Squirtle live in the terrarium of an elementary school class. For decades they have observed the students' development, they understand children's psychology quite well, and they can even talk, but they hide this from people. One day Leoi overhears that lizards of his kind live up to 75 years, and when he calculates that he is already 74, he is horrified to realize that life has passed, and he hasn't really seen much of anything. At that very moment, a substitute teacher decides to teach the children responsibility and assigns taking the class pets home for the weekends. Leoi tries to take advantage of this opportunity to break free, but in the process he blabs and is now forced to give life advice to the fifth-graders so that they won't tell anyone about his secret.