勇者王ガオガイガー
The "deluxe" version of the "-Grand Glorious Gathering-" DVD box set contains a special disc called "Disc Z." One of the features on this disk contains information about a new "GaoGaiGar" work entitled "The King of Braves GaoGaiGar Project Z". This project brings "GaoGaiGar" in even closer relationship with "Betterman" by reintroducing the corporation Akamatsu Heavy Industries. They cooperate with GGG to build the "Neuromechanoid" Kakuseijin GaiGo, with "GaoGaiGar" characters Mamoru Amami and Ikumi Kaidou as its "Head Divers" (pilots). Betterman Lamia is also seen to make at least one appearance. No further information on Gaogaigar Project Z was revealed for about a decade, and only in 2016 did it resurface under the new title "Hakaiou ~GaoGaiGar VS Betterman~". The renamed work was penned by series writer Yuuichirou Takeda and published in novel format online at Yatate Bunko.