Kenta Watarai (渡会健太 Kenta Watarai) is one of Hikaru's childhood friends and also one of the main characters in Ultraman Ginga.
One of Hikaru's three childhood friends, Kenta's family owns a photography shop which inspired him to be a professional photographer. However in the present he had not accomplished that goal. He may also have a crush on Misuzu and is unaware of Chigusa's feelings for him.
Later, in episode 10, Kenta and Chigusa join Seiichiro in fighting Super Grand King after receiving Ginga Light Sparks. Kenta picks Ultraman Tiga and Ultlives into him, but the trio are ultimately defeated after an immense effort. Though it seemed that everything was over with Misuzu and her father reconcile, the dark force re-possess principal Kyoko Shirai and awaken his true form: Dark Lugiel. The villain smashed their school and defeated Ginga, causing everyone to fall into despair. It wasn't until everyone hold on to their hopes again and Ultlive Taro into his true form to battle Dark Lugiel and revive Hikaru/Ginga. With Ginga revived, he took the whole battle with Dark Lugiel to the moon and destroyed him with his Dark Spark via Ginga Especially. With the battle is over, all Spark Dolls returned back to their homeworlds and Ginga and Taro bid farewell to everyone. Kenta and his friends (including Hikaru) hold each others' hands and jumping along in a circle cheerfully.
Kenta and Chigusa were walking at Tokyo when suddenly, they witnessed Alien Magma wandering around. As they trailed the alien, Magma realised this and getting mad as he chase the two until he decide to corrupt Chigusa's heart and forcing her to Darklive with Zetton. Fortunately, Kenta snapped Chigusa out of it, making Magma angered and Darklived himself into the monster. Chigusa and Kenta Ultlived into Ultraman and Tiga. They transform and force Zetton away from Earth and onto the Moon, beginning their fight.
Tiga and Ultraman fire their beams at Zetton, but he vanishes and attacks Ultraman from above. Ultraman blocks the attack, and Tiga manages to send Zetton flying with a kick, causing him to land heavily on the ground. Ultraman grabs Zetton and Tiga charges up his Zeperion Beam. But before Tiga can fire, Magma sneakily escapes from inside Zetton and strikes Ultraman from behind. Zetton and Magma strike at both Ultras, leaving their Color Timers blinking.
Zetton fires a fireball towards Earth, but Ultraman and Tiga use the last of their energies to take the attack upon themselves. They assert their determination to protect the Earth from Magma, Before he can land the final blow though, Ultraman Ginga reappears in the nick of time and blocks Magma's blade with Ginga Saber, before taking the fight to Magma and Zetton. Overpowering the aliens, he ends the fight with a powered up Ginga Cross Shoot.
Tiga and Ultraman's time limits are almost up, and Chigusa and Kenta panic, not wanting to die in space. Ginga gets to them in time and returns them to Earth. As the two awakened, they thought the previous event was a dream.
Two years after Ginga's battle with Dark Lugiel ended, Kenta had achieve his lifelong dream to become a photographer. He was seen in charge of Chigusa's filming and photography during her performances. In the last episode, he helped Chigusa air her performances to encourage human survivors of Vict Lugiel's rampage.
- Dark Dummy Spark: In episode 5, Kenta was given the Dark Dummy Spark by Alien Valky like Chigusa. He use it to Darklive into Jean-Nine.
- Ginga Light Spark: Kenta was also given a Ginga Light Spark, which allows him to Ultlive into Ultraman Tiga's Spark Doll. With the Ginga Light Spark, he can communicate with others through telepathy. With Misuzu's Ginga Light Spark, he had Ultlived into Jasyuline along with Chigusa and Misuzu. This allows them to control the monster and fight together.