The Light at Night in Summer

Hirofumi Mizusawa is a second year student at Nanagou High School, which is going to close this summer. One day late at night while trying to finish his summer homework, he observes a "flying orange light" from the window in his room. The next day, he tells his friends Akira and Ryo about it, and they begin to investigate the true nature of the light, but... (Source: YouTube, edited)