Springtime rolls in at last, and a form of seasonal laziness begins to affect all people - which inspires Keroro's latest scheme, to channel the energies of the world's laziest lifeforms and use it against the people of Earth. Kururu creates a reactor chamber to house this 'Keron March Energy', and a successful test with 556 as the subject is run, but things go horribly wrong when Kururu opens the reactor to let out 556... and all the Keron March Energy at the same time...
Keron March Energy spreads rapidly throughout the city, and it's up to Fuyuki, protected from the ominous fog by his diving suit from episode 20, to put a stop to this. Making his way through the underground base, Fuyuki uncovers one cryptic clue after another, and finally locates Keroro - trapped by the now self-aware Keron March Energy (bearing a strange resemblance to Ayanami Rei of Neon Genesis Evangelion), which threatens to bring about the end of the world with March Impact.
