Where does the Sea Begin

When and how does one become a “father” and a “mother”? A story of “family”depicted through the “love between parents and children".The protagonist of this story is Natsu Tsukioka (Ren Meguro). He was living a happylife with his classmate, Mizuki Nagumo, whom he started dating on a whim during hiscollege days. However, one day, just as he was about to start job hunting, shesuddenly broke up with him and they parted ways. Seven years later, Natsu wasmoving on with her life, when she received a call from a friend from college informingher of Mizuki's death. She had never seen Mizuki since the breakup, and he went tothe funeral without really feeling it, where he met a young girl named Umi (RanaIzumiya). Natsu cannot hide her surprise when she finds out that the girl is Mizuki'schild. Her mother tells her that he is Umi's father. He learns that Mizuki had a childwith him without his knowledge and raised it without saying a word, and he thinksabout the seven years that Mizuki and Umi spent together...