Takeshi (Takashi Tsukamoto), an Italian restaurant chef, and Ruri (Saki Aibu) could have been lovers, but Takeshi was too comfortable with their current relationship that he chose to stay best friends with her. Now, Ruri is engaged to another man and Takeshi is deep in regret. He runs through the night of Tokyo to tell her his true feelings before it’s too late, but right as he stands in front of Ruri, an unfortunate accident takes his life away. However, a twist of fate brings them back together once again in an ironic situation. "Eternal First Love" unfolds as a bittersweet story of an everlasting "first love."

Kazuhiko Kogure, who is a 2nd grade student in middle school, falls off from one of the school's rooftop. There were other male students on the roof when Kazuhiko Kogure fell off. According to the other students there, Kazuhiko Kogure tried to jump to another school building, but missed. Fortunately, Kazuhiko Kogure only fractured his leg and ribs. According to Kazuhiko Kogure's mother Hidemi, the school insists it was students playing around and did not involve bullying. Hidemi though, doesn't believe it, because Kazuhiko Kogure has a fear of heights. Hidemi goes to see attorney Machiko Mayuzumi and Machiko decides to take her case, but she asks for fellow attorney Kensuke Komikado's help. Meanwhile, the school hires attorney Teshigahara Isao.