Nageki no Doukutsu

The Caves of Grief is a location in the Inazuma Eleven GO Chrono Stone series.

Info (Chrono Stone)
Master Dragon is said by King Arthur to live here. In episode 36, Nanobana Kinako was kidnapped by Master Dragon and returned back to here. There, Kinako was kept prisoner. When Raimon arrived there to save her, King Arthur had a battle with Master Dragon which resulted in Master Dragon falling into a river, making people think she had died. After, Tenma confronted the dark knight, asking why he was making Master Dragon do bad things. The dark knight revealed himself to be Rei Ruhk, and then had a match with Raimon.