NieA_7 - Season 1 Episode 10 Glow of the Firefly & Nocturne Bath

When the restaurant that Mayuko works at gets a large party reservation, Mayuko goes to the supermarket for ingredients. Chie goes with her which turns out to be fortunate since Mayuko has never been inside a supermarket before. After the party leaves the restaurant, Chie sees fireflies for the first time and her father tells he about how Enohana used to be known for them - so to speak. NieA still tries to figure out what the mothership means by the "sayonara" signal she picked up.