第4話: ヒナタ家へ罠を仕掛けるギロロと、湿度の変化で狂暴化するケロロ
"Giroro: The Most Dangerous Man in the Universe, Sir!": Giroro is disgusted by Keroro and Tamama's lack of progress in the invasion and decides to set traps for the Hinatas using all the information he had gathered on them. He immobilizes both Keroro and Fuyuki, but Natsumi easily overcomes the traps with her brute strength and knocks out Giroro. "Keroro: An Occasionally Dangerous Man, Sir!": Giroro suspects that the reason behind Keroro's lost interest in the Pekoponian invasion comes from a difference in humidity between Earth and Keron. He and Tamama install humidifiers in Keroro's room, which drastically increases his intelligence and strength, but the room becomes overly humid when it begins to rain, causing Keroro to go berserk. The humidity attracts a Nyororo, a natural enemy of the Keronians, which feeds on all the moisture Keroro had absorbed and returns him to normal. (Source: Wikipedia)