This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
Strider
Hiryu is Bakuryu all grown up. On steroids. With a girlfriend. With no emotions. With an eyebrow implant
They look very similar
Hien is related to Kid Blue from Bomberman
They are naive and childlike
