Jinrui wa Suitai Shimashita

Humanity has experienced a significant decline over the centuries due to a sharp decrease in birthrates, leading to the rise of "Fairies" as the dominant species on Earth. These 10 cm tall beings possess high intelligence. The protagonist, serving as a UN arbitrator between humans and fairies, returns to their hometown to assist their grandfather. Assuming the role would be relatively simple, they visit a fairy habitat to greet the inhabitants, only to encounter unexpected challenges.