"She's a model for all princesses, a shining example for all young girls. By giving herself to eternity, she began a journey of infinite wandering. She lost interest in all there is, save for what goes on in the humans' minds." Kaguya Houraisan is a Lunar Princess who lives in Gensokyo. She enjoys chatting about history and loves rabbits. If you've somehow wound up in Gensokyo, that's no trivial matter.

The Lunar Capital Expo is an event organized by Kaguya Houraisan. It's held once per year, almost always at Eientei. Attendees get the chance to see a collection of rare items from the Lunar Capital. The items on display are split into several categories, including "classic," "military," and "academic." All the items are said to be from Kaguya's own collection and completely authentic. The aim of the expo is to garner interest in the Moon (and to make a profit). Kaguya can never return to the Moon, so from her perspective, the expo serves as a precious reminder of what life was like in the Lunar Capital. And from the denizens of Gensokyo's perspective, it gives them a chance to feel like they're on a trip to the Moon.

The Lunar Capital was built long, long ago by Tsukuyomi. It lies on the far side of the Moon and is protected by the Moon's barrier. Little is known about the city, and the relationship structure between its elites appears to be rather complex. Within the city, information suppression and manipulation are commonplace. Where Gensokyo is a settlement nestled among mountains on Earth, the Lunar Capital looks more like an ancient Chinese city. However, it's far more technologically advanced than it appears, thanks to their knowledge of super-science. The Lunar Capital once waged war against the youkai of Gensokyo. It's said they also once fought against humans from the Outside World, but there are far too many unanswered questions to be certain such a conflict took place. That said, some youkai remember a time when citizens of the Lunar Capital and of Gensokyo got along. Eirin Yagokoro now lives on Earth, but it's rumored she still exerts great inflict on the city from afar.

Chang'e is a Lunarian Goddess who drank the Hourai Elixir to become a person of Hourai. For her crime, she was sealed away in the Lunar Capital. As the ruler of the moon rabbits, it's thought that she played a hand in making them the way they are. However, little is known for sure. It has come to light that the physical manifestation of the Lunar Capital Expo has perfectly replicated Chang'e's personality and firmly believes itself to be her. The root cause of this is the fact that the Lunar Capital has been using Chang'e as a part of the city infrastructure―in other words, as a tool. It's impossible to differentiate between a specific person who's part of a collective and someone who's been made into a tool.

Various tools exist on the Moon, but the most advanced of which surely have integrated production, maintenance, and recycling functionality. If you focus your efforts on progress, eventually, you'll rid yourself of all redundancies. The Moon rejected the Earth's impure conflict-orientated mindset and focused on its own progress... At least, you could theorize that to be so. Perhaps Eirin Yagokoro's medicine is an example of what comes from pursuing progress. If the medicines Eirin makes are not known to science, the answers may lie in her omnipotent ability or the make-up of the Hourai Elixir. To phrase it another way, her medicines may consist of nanobots. At least, that's the theory that I, Chiyuri Kitashirakawa, wish to propose. Phew... Finished. I reckon the reports I write sound preeetty good.