When Jin's crew about to be eliminated, a being with light silhoute destroys them and let the remaining Gyashi flew safely. As the Alien Gyashi migrated, Scorpiss chase them and destroy them. Shau reveals that sometime ago, Sandros and his Scorpiss terrorize their planet and turn it into a wasteland. Mari appears and leads them to their base where she revealed that Child Baltan from 10 years ago that brought her to this place.
Musashi encountered him earlier in a dream where he got destroyed by Jin. Once arrived, they were introduced to Alien Gyashi, where their leader, Jin, holds a dislike towards humans for being selfish. Soon the Team SEA is led by Shau and Reija under the sea to where a portal opens, leading to her people's hideout. Scorpiss retreated for a while and the mermaid reveals her name as Shau while telling Musashi that Mari is with her people. However, all he foreseen was a dream and realise that Cosmos will never return. The phantom-looking Ultra rescues Reija and overpowers Scorpiss while destroying it with Phantom Blazing Waze. Musashi takes his Cosmos Stone and transform into Ultraman Cosmos Phantom Corona Mode. There, he witness the mermaid, now having a human legs fuses with Reija, turning the monster stronger but still, overpowered by Scorpiss. Musashi exits the TROY BS and bring his friend to safety. Reija appears and fought the monster but only to be overpowered by the menace. Once they about to be killed, Team SEA fires a missile, bringing it away from the hospital. As the monster rampaging at the city, it begin to destroy a hospital that Musashi's friend reside. Musashi joined by Team SEA launches with their TROY AS and TROY BS. Musashi recognise him earlier for turning Juran into a barren wasteland and killing Parastan. They were interrupted by a warning where a monster named Scorpiss entering the Earth atmosphere.
Musashi was taken to their base and revealed that the monster he encounter earlier was Reija, who was detected undersea a year ago. Then, Koji, an original member of SRC and now a captain of Team SEA approaches him as he glad that he survives. He awakens at the hospital as his friends visits him but Mari was nowhere to be seen. The man decide to eliminate Musashi for interfering them but the objects, only for too late as he already fire an energy blast to Musashi. One a man and the other a woman/mermaid that he witnessed before. As Musashi about to follow Mari, he knocked down unconscious. The next day, when Musashi and Mari went snorkelling, they discover a portal underwater and at the same time ambushed by a stingray kaiju. As it starts to rain, Tutomo cowardly hides under the table with Mari mocking him, causing Tutomo to take a nearby soda and spraying it on Mari, starting a soda fight with his friend as they watched again by the mermaid. One of his friends, Tutomo, mocking him for believing he saw a mermaid but Mari objects, implied that Musashi might be talking the truth ever since his first encounter with Cosmos. During her lunge, Musashi saw a strange woman in the ocean, who suddenly leapt into the air, proving to be a mermaid. Musashi attended his childhood friend's wedding in Saipan. Cosmos destroyed the monster, causing a giant explosion and quickly rescuing Musashi from the explosion. As they dueled, Musashi founded that the monster is responsible for turning the Planet Juran into a barren wasteland via its energy beam. As it about to ram Musashi's TECCH Spinnar KS-1, Ultraman Cosmos appeared and save him. Suddenly, a flying monster burst out from the ground and firing a reddish energy ball. Not only that, Parastan, the Planet's protector died. However, much to his horror, the planet appeared to be a reddish and dusty wasteland. TECCH Spinnar KS-1 and went on a journey to Planet Juran. It has been a year Musashi retired from being a Team EYES member and now he has finally pursuiting his dream to become an astronaut.