Mount Hitoki

Mount Hitoki (灯溶山) was a mountain which served as the lair of the Gurongi in the World of Kuuga.

The backdrop used to arrive in World of Kuuga shows a city with police cars and Mount Hitoki in the background.

History
Tsukasa Kadoya deduced that the lair of the Gurongi was Mount Hitoki from the locations of four Grongi attacks on police women, killing them without shedding blood, each taking place in different directions but the same distance from the mountain. On the foot of Mount Hitoki, Tsukasa revealed he used Ai Yashiro as bait to lure out the remaining Grongi, revealing their plan to revive their leader before ruining their game by giving Ai a bloody nose.

When Ai and her task force gone to investigate Mount Hitoki, a black mist began to rise from within, signaling the revival of N-Gamio-Zeda. Resurrected by the dimensional chaos, he used his miasma to convert humans into Grongi. While Yusuke saved Ai and took her to the hospital, Tsukasa fought the Grongi alone. A dying Ai requested Yusuke to overcome his angst and fight to protect everyone's smiles, and so Kuuga and Decade worked together to destroy the remaining Grongi. N-Gamio-Zeda, in a last effort, absorbed all the Grongi to power himself up, but he was ultimately overpowered by both Decade and Kuuga, who destroyed him with a combo attack. After returning to the hospital, Yusuke found that Ai had died and vowed to honor her dying wish, setting off on his own journey, joining the Hikari Studio.