Subtitle: Space-Time Monster (時空怪獣 Jikū Kaijū)
Dairyuhai was said to be the sister of the younger Otohime, as well as her protector. When Urashima Taro washed ashore to the present time and broke his promise with older Otohime by opening the shell-shaped tamatebako, the younger Otohime arrived there and pursued him. When Taro, now an old man as a result of breaking his promise, returned to the beach and met the younger Otohime, she berated for what he had done and as a result of that, her sister died. She threw the tamatebako into the sea and from there Dairyuhkai emerged, much to Taro's shock.
While she was about to take rampage on Ryunomiya City, she was stopped by Ultraseven who attempted to held her off. Seven then hit Dairyuhai with the Eye Slugger and pierced her hand, but the monster stopped it and threw the blade away. During the battle, Dairyuhlai questioned him why did he protected humans that tended to break promises. Taro later showed up and offered up a moonflower, showing that he had kept his promise, that she absorbed him and relented disappearing in a golden light (tachyon particles).
- Suit Actor: Fujimoto Kotaro
- Dairyuhkai is one of the few monsters to fight an Ultra and not be defeated nor defeat said Ultra since their fight was not completed.
- Despite being listed as a Kaiju, Dairyuhkai is actually clearly sentient, given her motivations and the fact she spoke to Seven.
- Her roar is composed of a monster's roar and a woman's scream.
- Height: 61 m
- Weight: 50,000 t
- Origin: Pacific Ocean
- Powers and Weapons
- Tornado: Dairyuhkai can create or emerge from a tornado.
- Blast Cannons: Daiyruhkai can fire several missile-like blasts from her mouth at once.
- Smokescreen: When needed, Daiyruhkai can emit a steady stream of blinding mist from her mouth.
- Telepathy: Dairyuhkai can talk to others telepathically.
- Thick Skin: Dairyuhkai was able to stop the Eye Slugger after it struk her hand.