This is the story of a beast-youkai shikigami and her investigation. Her current name is Ran Yakumo, and her shikigami master is Yukari Yakumo, one of the Sages of Gensokyo. She does whatever her master tells her to, from investigating incidents to battling insolent humans. On this occasion, she was tasked with investigating the peculiar actions of spirits following the marketplace god incident that affected ownership rights. Doubting anything serious was afoot, she planned to wrap up the investigation quickly and report back to Yukari. However, as her investigation dragged on, she was forced to face the past she had left behind. She met a familiar face in what should have been an all-too-familiar place.

This place was the Animal Realm. It had been so long since she'd last been there that she barely recognized it. Looking down upon the never-ending sea of buildings, she lamented that it had become a metropolis. What did it look like before? Did it resemble the opposite of a metropolis―like a run-down village? Or was it more in line with traditional depictions of Hell―a vast wasteland with no buildings in sight? If you asked Ran, she'd probably refuse to answer... but some people have lived in the Animal since then and continue to live there now, such as Yuuma Toutetsu, the leader of the Goyouko Alliance. She could tell you all about the Animal Realm and the old Ran who used to live there.

Only those involved truly know what happened between Ran and Yuuma. However, judging from what Yuuma said to Ran recently, it's possible that Ran, as a youkai beast, used to be just as dastardly and ambitious as all the other denizens of the Animal Realm. If Ran never left the Animal Realm and never became a shikigami, would she and Yuuma be partners now, leading the Goyouko Alliance together? Or would they be vicious rivals, with Ran leading her own clan? If such a world exists, the animal spirits there may well have conquered Gensokyo or, at the very least, entered into a protracted war with the shrine maiden and the sages.

You can forget the past, but you can't undo it. You can leave the past behind, but you can't outrun it. The past cannot be changed, so when it finally comes time to face it, you have two choices―turn back and embrace the past or accept it and move on into the future. What choice did Ran Yakumo make when she battled Yuuma?

This story is still ongoing. Both the past and the present exist. But the future only exists beyond the present. What future awaits Ran after facing her past in the form of Yuuma? Will she oppose Yuuma's plans at every turn, or will they help each other out? Only she knows for sure. Perhaps that's what this busy shikigami was thinking about when she set out on her next investigation as the Sun shone and the rain poured down on Gensokyo in equal measure.