High school student Seiya Maki fell in love at first sight with the lunch box that Arisa Asahina, the most beautiful girl in her class, made one day. "I want to eat Mr. Asahina's bento, so I want you to go out with me." Thinking that she was made fun of by his confession, Arisa gets angry and throws Seiya off, but she gradually becomes attracted to his innocence and his kindness in helping her with her troubles. However, one day, Arisa discovers a secret that Seiya cannot tell anyone. Where will their relationship go, and why is Seiya attracted to Arisa's bento? Painful, bitter, lovely, and beautiful. Youth story begins.