Kyouko works at an izakaya with her brother. She's in love with Midori, one of their regulars. At the start of series Midori breaks up with her cheating boyfriend and becomes friends with Kyouko.
Midori takes Kyouko to an aquarium in chapter 19. The Japanese serialization has just ended at chapter 21.
Spoilers for the ending
Midori planned to use the aquarium date to confess and ask Kyouko to be her lover, but she gets a bit ahead of herself and kisses Kyouko without confessing. This causes Kyouko to run out of the aquarium, but after some words of encouragement from Kyouko's brother and Midori's ex, they do manage to do their confessions properly and become a couple before going home from the date.