I can't for the life of me remember the title of this manga. Its about a brother and sister who are not blood related, but who are living together after their parents die. Each chapter concludes with one or the other cooking a meal. I remember that one chapter is about the girl researching perfect fried rice (I think) at a café every day. Another detail: the girl who is interested in the boy (they're in elementary school) is nicknamed "Long Kiss Goodnight."
Thanks for the help.