>>1096569
>>1096569
Now this is one of my favorites.
Not many people know that the Youkai Mountain is also connected to the Yatsugatake Mountains outside of the Barrier, making Youkai Mountain also part of it. Or rather, Youkai Mountain IS Mount Yatsugatake. This is easily connected using canon info.
Konohana-Sakuyahime was a water deity who calmed volcanoes. Her older sister was Princess Iwanagahime, the God of Immortality, who resided on Mount Yatsugatake, or Youkai Mountain, as people of Gensokyo called it.
Sakuyahime is a bit more known than Iwanagahime (thanks to popular media like Persona). In Japanese mythology, Konohana-no-Sakuyahime (木花之開耶姫) is the goddess of Mount Fuji and the daughter of the mountain god Ohoyamatsumi. She is the blossom princess and symbol of delicate earthly life whose image is that of the sakura.
The wife of Ninigi-no-Mikoto, they met at the seashore and fell in love. Ninigi asked Sakuyahime's father for her hand in marriage, but his other daughter, the rock princess Iwanagahime, was offered instead. Ninigi refused, and Ohoyamatsumi relented. Ninigi taking Sakuyahime instead of Iwanagahime is said to be the reason why human lives are short and fleeting, like sakura blossoms, rather than enduring and long-lasting.
Back to the present, Sakuyahime and Iwanagahime were intrinsically tied to Mokou's backstory. A long time ago, the Emperor ordered a retainer, Tsuki no Iwakasa, to dispose of a batch of Hourai Elixir. He was given an entourage of guards and ordered to set forth to Mount Fuji and toss the Hourai into its' volcanic flame. Mokou somehow was able to accompany them.
On top of Mount Fuji, Sakuyahime appeared before Iwakasa and his men and Mokou and warned them not to throw the Hourai into Fuji, for it would cause Fuji to become active again. They spent the night on the mountain, but Sakuyahime awoke Mokou and Iwakasa and claimed that the men had started killing each other over the elixir, although Mokou speculated that she thought Sakuyahime had killed them herself. Sakuyahime directed them toward Iwanagahime on Yatsugatake, which was more equipped to deal with the Hourai Elixir.
Presumably, Mokou killed Iwakasa on the way down to steal the Hourai Elixir, as there were no more guards left. From canon mentions, Mokou notes that one day she wants to travel to the top of Youkai Mountain, presumably to pray to Iwanagahime and to apologize to her for what she did to Iwakasa. Again, the Youkai Mountain of Gensokyo is connected to Yatsugatake, where the goddess resides.
If Iwanaga is to make an appearance, the setting should be near Youkai Mountain or within its' bowels and underground. More lore for Mokoufags out there.