Kelvin Stelar

Kelvin Stelar, Hoshikawa Daigo in the Japanese version, is a character from the MegaMan Star Force series. His role is like that of Yuichiro Hikari's. He is an astronaut who went missing a few years before the first game. He was captured by the FM-ians while trying to form a BrotherBand with them, but Omega-Xis turned him and his crew into EM waves so that they could survive in space. Unfortunately, they were lost.

Game History
When Andromeda goes out of control in MegaMan Star Force and almost eats Cepheus, Kelvin reminds Geo that everyone had counted on him, and that he must fight on, which gives him the strength to stand up and deal the finishing blow. After Geo is forced to take the escape pod of the space station back to Earth, but finds that he cannot properly navigate it, Kelvin appears in a dream, telling Geo to trust in his friends. This ends with Geo finding the BrotherBand link from his friends back on Earth, allowing him to follow it home. In the Deep Space Comp, Geo also finds Kelvin's Transer, along with the Kaiser Knuckle weapon and a message to Geo, explaining his fate.

In MegaMan Star Force 3, he is found to be inside Meteor G (as he had been converted to EM waves by Omega-Xis). When he discovered it as he was making his way back to Earth, he saw how grave a threat it was and entered it to try and stop it. It was his fight that prevented King from harnessing Meteor G's full power and bought WAZA enough time to prepare their plans to destroy it. Hope Stelar gives Geo the "Kelvin Code" (Daigo Code) which plays a vital part in the final stage of the game as it helps locate Kelvin's memories throughout the Meteor Server, chronicling part of his travels through space and some of his time before leaving on his mission. At the end of the stage, Geo finds Kelvin standing in front of the core, only for him to be sucked in when the Crimson Dragon is summoned.

After the defeat of the Crimson Dragon, Kelvin calls out to the Hunter VGs of those all over the Earth, telling them that Geo may not make it back and his sacrifice was not in vain. This inspires the people of Earth all to form a Purpose group to help guide Geo back to Earth. Kelvin tells Geo to use the resultant Purpose Wave, telling him that he and Omega-Xis will return when the time is right. As Geo unwillingly drifts back towards Earth, he finds a last piece of his father's memories left behind by Meteor G about the day of Geo's birth, and eventually hears the people of Earth calling for him. Without a regret, Geo rides the Purpose Wave back to Earth.

Some time after his return, Geo is seen watching the sky, thanking Omega-Xis and Kelvin for their efforts. Then, a shooting star is seen headed towards Geo, and it turns out that Omega-Xis found a way back. A second shooting star is then seen headed towards them, which Geo and Omega-Xis stare at, talk a little, and walk home. Later at home, Geo returns to his mother, revealing that Omega-Xis and Kelvin have made it back to Earth safely (Omega-Xis comes in with Geo, but Kelvin surprises everyone by suddenly walking through the front door.

Manga History
Kelvin's background is the same as the game. After the tournament at the Wave Coliseum is over, Gemini Spark steals the Star Force to revive Andromeda,the king of the FM-ians. This story arc concludes with Mega Man discovering that Andromeda and his father Kelvin had fused as a single EM Wave Human. Defeating Andromeda, Kelvin is freed and returns to Earth to live with his family and new FM-ian friends.

MegaMan Star Force (anime)
He appears after the final battle with Andromeda when Geo asks Cepheus to show him his father. Kelvin tells Geo that he is safe in space, exploring other planets, and might not be back for a long time.

Trivia

 * There are unused sprites of Kelvin form MMSF 1 in MegaMan Star Force 2, and they are fully functional with hacking.