Obento meals are offered in all USA-JAPAN-USA flights in United First and United Business. I don't think they are offered in intra-Asia flights, although they are offered in NRT-HKG-NRT flights in United First. I'm not that excited about it, although they are definitely "different" and worth a try. (I guess I'm not that excited about airline meals at all, given that most on-the-ground restaurants I visit offer a wider selection and better quality food, sans warm nuts!) Call ahead to reserve one for your NRT-ORD segment, or they may be "sold out" by the time the FA asks you for your meal selection.