Ultraman Tiga: S1 E12 - S.O.S. From The Bottom Of The Sea Ultraman Tiga

Rena's subordinate's "lover," the dolphin Myu, hasn't been feeling well recently. It seems to be afraid of something. Just then, Monster Leilons, the monster that has been causing undersea earthquakes, appears. Myu's animal instincts sense the arrival of Leilons. Tiga comes to face Leilons who is threatening the peaceful ocean!