"A dream we had together a long time ago... I never thought that the day would come true when I grew up." Jun, who works at a university, is suddenly hugged by a man named Kate, who has come to Japan for work, saying, "I missed you!" Kate was the boy who saved Jun when he was alone in a foreign land when he was young. Jun is daunted by Kate, who is cherished as his "first love" and approaches him with a ferocious courtship!! ―If I told you that I loved you ever since that day, would you believe me? Dramatic love of [cheerful and bold half-boyfriend] x [returnee who wants to change herself]!