Where Does the Sea Begin?

28-year-old Natsu Tsukioka's world turns upside-down when he learns that his college girlfriend, Mizuki Nagumo, has passed away. Natsu attends the funeral while struggling with unresolved feelings and disbelief, as Mizuki had broken up with him out of the blue and they hadn't spoken since that day. To his surprise, Natsu meets a young girl named Umi – and Mizuki's mother informs Natsu that Umi is his and Mizuki's daughter that Mizuki had raised alone for the past seven years. Confronted with this new information, Natsu seeks to understand his newfound daughter and her relationship with her mother. Can Natsu develop his own parental bond with Umi and learn more about Mizuki's choice to leave him all those years ago?