There is an optional side story that happens by talking to Klia and Doran throughout the game, showing that they have developing feelings for each other.
Specifically, talking to Doran in Chapter 09, he will ask you what kind of gift you would like. You can answer Pot or Flower. I don't think the option matters, just that you talk to him.
During Chapter 10, he will show up on the city steps after you talk to the Indigo & Red Guardians and give her the suggested gift, which gives Klia an idea. She tells you to go to your house. There will be a surprise birthday party. If you saw the scene with Doran giving a gift to Klia, then Klia will give you a gift and the achievement will unlock.