(Based on the world view of the Touhou Project series, original plot, no systematic mechanism, micro daily life, no time travel, and no other elements except Touhou)
God said there should be light, so there was light, and chaos turned into night. Light is a symbol of human nature and night is the carnival of monsters. Eternal night is coming, the sun symbolizing humanity will never rise again, and the night symbolizing monsters will always exist. Welcome to Gensokyo, the unique fantasyland of monsters.
(Slightly OOC, the writing is quite poor, sorry everyone!!!)
