I accidentally sent multiple messages to the close friend group chat that were meant for a friend, and ever since the next day, one of my female friends has been acting strange... What should I do?

Koumei (Hiroaki) is an utterly ordinary high school student. Through a strange turn of events, he became close friends with famous people who represent the school. One day, while Koumei and a friend were texting on Line, they accidentally sent multiple messages to the wrong group chat. The next day, arriving at school with anxiety, his female friend's behavior seems odd. This is a story about an ordinary person forced to make a difficult decision. ※There may be parts that are difficult to see depending on screen size.