Thanks to this brand new Tiga review, I now remember that Daigo's son, Tsubasa, also became Tiga in a special episode.
I'm also surprised that there's a reference of Stephen King's
The Mist in the show. It reminds me of Kamen Rider Kuuga that paid homage to the horror movie
Black Christmas in the very first episode with the 1st person POV climbing the window (which turned out to be Godai instead of a killer).