Original: 海のはじまり
A love story depicting the connection between parents and their children in various forms.
Natsu unexpectedly learns of his ex-lover's death from a college friend and meets her unknown daughter at the funeral.
Natsu's girlfriend Yayoi, when she finds out that Umi is his daughter, gets upset.
Natsu recounts his separation from Umi's mother, unaware she was pregnant.
Natsu and Umi let go of the emotions that Mizuki's memories stir in them. Meanwhile, Yayoi is in a hurry to get answers.
Natsu wants to spend a week with Umi, so he asks Akane what she thinks.
Natsu and Umi spend a week together in the Negumo household, and Natsu thinks back to the life Mizuki and Umi led together.
Natsu and Umi spend the day at Yayoi's house, between homemade croquettes and impertinent questions.
Yayoi has mixed feelings about Umi, while Natsu has to deal with a mysterious person.
Natsu notices that Yayoi is flaunting strange behavior with Umi, who treats her as if she were her mother. The relationship between Yayoi and Natsu hangs in the balance.
Yayoi and Natsu break up, and the latter decides to live alone with Umi, realizing how difficult it is to raise a daughter alone.
Natsu feels guilty seeing Umi sad to leave her school and family to live with him.
One morning when Natsu wakes up, Umi is no longer in his house.
