Yu Hirama (平間優 Hirama Yū) is Tsutomo's friend and the supporting protagonist of the movie Ultraman Tiga, Ultraman Dyna, & Ultraman Gaia: The Decisive Battle in Hyperspace.
One day, Yu abandoned Tsutomo for a while as he can no longer withstand his antics over addiction towards Ultraman. The next day, after school, Lisa Nanase, a new student presented him and Yu the Red Sphere, capable of granting wishes. Witnessing his Ultraman Gaia drawing on the floor, this gave him an idea and wished Gamu Takayama to appear in his world. Hiroshi Kashimada, a bully sees this and confiscate the ball from him. He summoned Satanbizo via the ball and the alien rampaged with Tsutomo regain the ball. Gamu quickly transform into Ultraman Gaia and finished the alien with ease, despite having his Color Timer blinked in the beginning of the battle. Gamu was later brought to Tsutomo's hideout in order to cover himself from crazed fans. He revealed to Gamu that in his world, Ultraman Gaia is a television series and that it was him who brought Gamu in the first place. Tsutomo gave Gamu his favourite book, Gulliver's Travels which he accepted as he scanned the Red Sphere and the authorities surround him. Before the police forces could arrest him, Gamu forcefully teleported to Aerial Base.
Meanwhile, Hiroshi and his friends capture Tsutomo and Yu while regaining the Red Sphere in their possession causing it turned larger and grow spikes, even corrupting them. Hiroshi dragged Tsutomo and Yu to their school's rooftop and summoned his creation, King of Mons into reality. Lisa appeared, having watched the full event. However, Gamu appeared in the nick of time fighting the monster with his XIG Adventure and later as Gaia. However, the Ultra appeared having difficulty in battling the monster, Tsutomo removed the ball from Hiroshi, causing him and his subordinates to regain their sanity as they felt remorse of their actions. However, it landed on Yu's hands, corrupting him as he shouted his desire to destroy the world, spawning Bajiris and Scylla. As King of Mons' Cremate Beam hit the school, the ball moved from Yu's possession, regaining back his conciousness. Tsutomo quickly grabbed the ball and summoned Ultraman Tiga and Ultraman Dyna. After the Ultras finished battling the monster, the ball returned back to it's original form. Lisa revealed herself to be an interface of the Red Sphere. She urged Tsutomo to wish the ball to disappear, as he forcibly agreed, causing it to vanish, followed by Lisa, Tiga, Dyna and Gamu but not revealing that he can still meet him due to his book, returning it to Tsutomo's hands.
The same day later repeated by the Red Sphere but the real Lisa Nanase appeared as a new student.
- Yu's actor, Miyu Irino would later voice Jean-Nine in the Ultraman Zero specials.