On a summer day off, Yu, dressed in a bright sleeveless plaid dress with a huge black bow at the back, stood at the entrance of an aquarium—a modern building with a curved facade and large glass windows. In her left hand she held a small handbag, and with her right hand she was adjusting her hair, using the glass window as a mirror. But when Yu noticed Umika running toward her at full speed from behind, she got flustered and nervously started smoothing her hair. Umika was wearing a light summer dress with a black tie, and a white handbag on her shoulder. "Ah, Akeuchi! S-sorry, did I keep you waiting?" the out-of-breath Umika apologized...