Reiji

Unit:

[Spoiler] Build Strike Gundam, after being destroyed by Yuuki Tatsuya, Iori Sei evolved it to another level: Star Build Strike Gundam. [/Spoiler]

A mysterious boy Sei Iori encounters in town. He's overbearing, selfish, quick to anger and lacking in manners. Thrust into the Gunpla Battle cockpit, he shows off incredible piloting skills on his first try.

And has mysterious story about himself being a prince in the another world, Arian Kingdom