Facing the Sea of Japan in Yamagata Prefecture is an aquarium with one of the world's largest collections of jellyfish on display. The most popular attraction is a 5-meter-wide tank in which 5,000 moon jellyfish serenely drift around. Aquarium visitors include a high school student who dreams of becoming a rocket engineer as he gazes at jellyfish resembling stars in space, and a woman who watches baby jellyfish for 30 minutes. In the evening, others participate in an overnight event and sleep at the aquarium. For 3 days, we asked why people feel so deeply about these mysterious creatures.