Aki found this article snippet from Great Mechanics DX17 (summer 2011 issue) and translated it. It’s an interview with (most likely) producer Kazuhiko Tamura from Sunrise and it mentions an upcoming addition to the cast, Kotetsu’s older brother.
Well, Kotetsu emigrated [to Sternbild]. Right now, his mother is looking after his daughter, Kaede. But there is one more person watching over them – Kotetsu’s older brother, who’ll appear in the show soon. Kotetsu doesn’t want to reveal his hero identity, but his brother and mother both know about it, the only one in dark is his daughter.
We’ve seen a few mentions that he’s supposed to appear in episode 14 but we can’t confirm that without a source.
(Episode 12 post coming as soon as we can sort our thoughts on it. Geez, Sunrise…)
This is Sternbild 
I’m really curious as to how he’ll look and be like, I can’t wait!
But we have just seen him!!! He is that person near the Taxi that calls his name.
If it’s the scene I think it is, the person saying Kotetsu’s name was his former boss who sold his business to Apollon Media in the first episode (and looks like he ended up driving a taxi). The citizen wanting a ride from him just wants to get away because even heroes are losing to Jake.
Pingback: NEXTs – what we know and don’t know | This is Sternbild
Pingback: Episode 16 or the higher they are the harder they fall | This is Sternbild
Pingback: Opinion: Kotetsu isn’t a bad parent | This is Sternbild
Pingback: Episode 17 or finally family time | This is Sternbild