The experience of an ordinary high school student from his freshman year to his senior year has brought about earth-shaking changes in his life. He originally lived with his grandfather, and his life was dull but happy. However, he still met his "father" and "mother". His destiny changed, but he was no longer happy. Grandpa has always wanted to go to the sea. When he was really able to go to the sea with him, grandpa could no longer go with him.