Doing some research with chatgpt, I found that: Sakuya, whose name means 'flowering night' nocturnal and lunar theme + the lunar emissaries to bring Kaguya back + Eirin and Kaguya have been living in exile in Gensokyo for centuries, which shows that this event dates back to a very ancient time + Tsukuyomi is the founder and lord of the Lunar Capital. He is described as a wise man who left Earth thousands of years ago due to its impurities and took his trusted relatives with him, including Eirin Yagokoro