Please Make Girls Happy

Entrusted by her neighbor's aunt, Lin An planned to visit her childhood sweetheart after a long absence. They had less contact since high school, and they had no contact after they started working in society. For some reason, Lin An had some expectations. After all, he once secretly liked his childhood sweetheart. He tried knocking on the door, but found that the door was not locked at all. He entered the neighbor's house with bad thoughts until he saw his childhood sweetheart with her feet off the ground—— The process was unknowingly forgotten, and when he came back to his senses, he had fallen to the ground. "She is obviously a good person, why can't she be happy?" Lin An said. The unknown figure answered him: "You obviously just watched and didn't do anything, right?" Looking back at his failed life, Lin An was speechless and his consciousness began to blur. When he woke up again, he found that he was back in high school. The difference from before was that there was a box next to him. After opening it, there was a pendant inside, with the label next to it saying "Happiness Indicator". This thing seems to be able to see the happiness index of girls? A gentle childhood sweetheart, a lively school girl, a little devil's student council president... This time, he hopes that the girls he cares about can be happy.