Ultraman Regulus is connected to Leo and Astra in some form.
His looks imply he's from the same planet, and with Absolute Tartarus' time manipulation abilities he could be from the far future or the distant past. Or from somewhen more recent, and is either Leo and Astra's father or one of the Brothers' son.- Confirmed. He had developed a friendly rivalry with Astra in the past.
Alternatively, Regulus has no connection to Leo and Astra.
Confirmed. He hails from planet D-60.