Touhou 12: Undefined Fantastic Object

During the events of Subterranean Animism, the action taken by Kanako Yasaka and Suwako Moriya towards their "industrial revolution" project for the Youkai Mountain - giving Utsuho Reiuji the powers of the god Yatagarasu in order to invoke nuclear fusion deep underground - ends up causing geysers near the Hakurei Shrine to spring forth, bringing evil spirits with them.

In early spring, after the snow begins to melt, rumors spread of a strange flying object in the skies. Believing the object to be a treasure ship, Reimu Hakurei and Marisa Kirisame are prompted to chase after it. In turn, they are followed by Sanae Kochiya.