As Nozomu leaves for a friend's birthday party, Hyde leaves to pay his respects to a fallen Seaick Gosei Angel until he sees the last person he ever expected to see: Luview Alien Kurasuniigo of the 5000°C. Losing his cool at the sight of the monster, Gosei Blue battles Kurasuniigo and loses to the stronger opponent as the other Goseigers arrive. Gosei Blue tells them not to interfere with this fight, surprising the others. When Kurasuniigo takes his leave, the others demand an explanation for Hyde's sudden change of behavior as the Master Head appears on Datas's screen and asks Hyde if he has forgotten his mission as a Gosei Angel. Hyde leaves as the Master Head reveals that Hyde had a partner as a Seaick Gosei Angel whom he fought alongside with named Magis until they both fought Kurasuniigo. In that fight, Magis as Gosei Green sacrificed himself to save Hyde, and Hyde blames himself for his best friend's death at the hands of Kurasuniigo. The next day, Hyde uses Datas to find clues about Kurasuniigo, until he overloads Datas's processors. By then, Professor Amachi arrives with a friend of his, Professor Sakana-kun, who is as much of a fish fanatic as Amachi is into the stars. The others have Hyde help out the young professor, seeing the man's aquarium which reminds him of his duty as a Gosei Angel. Elsewhere, the other Goseigers fight Kurasuniigo as he is evaporating the sea with his heat powers. The four lose until Hyde arrives with the intent to protect the sea rather than take revenge. Gosei Blue manages to defeat Kurasuniigo before the Gosei Buster is formed to take the monster out. Gosei Great is then formed to fight the enlarged Kurasuniigo, overcoming his heat attack with the Seaick Brothers before becoming Seaick Gosei Great to destroy Kurasuniigo. Later, Hyde returns to pay his final respects to Magis and ask him to wish him luck in fulfilling his mission before the others arrive to cheer him up.