Protect the Field of Flowers!
During an excursion, the boys of class 5-3 gets into a fight with the boys from the local. Meanwhile Kouji meets a girl called Kozue, who explains that the locals are angry that more and more trees are being cut for the expansion of the park for tourists. The next day, Class 5-3 hears that Onoboori mountain (the place they went yesterday) became treeless and a Jaku Beast is attacking. Still remembering the fight, Jin is reluctant to sortie. Kouji insist, saying it's their duty as the defenders of Earth and manage to convince everyone including Jin. With the help of the locals Raijin-Oh manage to defeat the Jaku Beast.
Aired 24/04/1991EP 4 - Protect the Field of Flowers!

Matchless Raijin-Oh
Suddenly, an evil empire, Jaaku, raids the Earth. But the light appears from the Earth, and fights against Jaaku. It is Raijin Oh operated by Eldran. Eldran has protected the earth since the ancient ages. But he was injured during the fight, and Raijin Oh falls to the ground. On the other hand, Jaaku scatters their weapons, Aku Darmer, all over the world.
Meanwhile, in Yosho elementary school, they have extra lessons in the 3rd class of the 5th grade. Eldran leaves Raijin Medal to them and asks them to save the Earth for him, and then he disappeared. In this way, the Earth Defense Agency consisted of elementary students is founded.
(Source: AnimeNfo)