Ordinary office worker Nonomiya Ryota (played by Masaharu Fukuyama) and his wife Nonomiya Midori (played by Machiko Ono) have been married for many years and have a very good relationship. The two raise their smart and well-behaved son Nonomiya Keita (played by Ninomiya Keita) together, and their lives are full of happiness. What the three people who thought that their peaceful life would continue did not expect was that a call from the hospital where Keita was born brought this small family to the cusp of the storm. It turns out that Keita is not the son of Ryota and Midori, but the fruit of love between Saiki Yudai (played by Lily Frank) and Eucalyptus (played by Yoko Maki). Is the relationship of being together day and night precious, or is the bond of blood connection important? Faced with the consequences of a small misunderstanding many years ago, Ryota and Midori don't know where to go. As for Yudai, Eucalyptus and their child Saiki Ryuharu (played by Huang Shengxuan), they are also standing at the crossroads of life.