bento box catering at Osaka Castle

Does anyone know if they sell food like Bento Boxes at Osaka Castle at Cherry Blossom viewing time?

packing food is not advised. however you may bring yours, but not not eating anywhere. only a very certain places.

It is not very common to sell bento at stalls outsides like park, etc.
People buy bento at department stores or terminal stations before going to parks for hanami (watching and appreciating sakura).
I recommend to go to the food hall on the basement of department stores, you'll find wide variety of bento, especially at hanami seasons. They sometimes even sell 'hanami' bento. :)

Normally families might bring their own (cooked at home), and larger groups (like college friends or company colleagues) buy food elsewhere and bring their food, and larger groups try to secure "ground" space to eat on. It depends on how crowded the place is when you go, but you might just want to have a look, see if it's likely you find space, and then go to a convenience store to get some food if you want to sit down to eat. You might just enjoy a walk-through cherry blossom viewing, and then later eat somewhere else as well. It "can" be still pretty cool outdoors at that time of the year.

Check out the cherry blossom reports under Travel section to see if you can find some photos of Osaka Castle during that time of the year :)