It was obviously a low season for birding when we arrived at Osaka on the third week of May. We did half-days birding from May 13 to 17 at two different places - the Osaka Castle and Osaka Nanko Bird Sanctuary. We saw a total of 30 species and got 7 lifers.
Osaka Castle Park. The wooded area surrounding the castle is a good place for birding. The three times we went there we saw bird photographers hanging around. The month of May was the best time to see the Japanese Paradise Flycatcher. The Park is easily accessible via commuter train. It is within walking distance from the Morinomiya Station. There is a convenience store (Lawson's), Starbucks and R-Baker, a bakery/restaurant near the entrance to the park. Come early if you plan to go birding to avoid the crowd. Also it is recommended that you visit this place in early spring to see more birds.
Osaka Nanko Bird Sanctuary. This place is for bird photographers. It has a semi-circular concrete structure with windows facing the wetlands. Chairs are even provided for photographers. Again the best time to be here is during spring and autumn migration. It is within walking distance (less than a kilometre) from the Trade Centre train station. There aren't any stores/restaurants within the vicinity but there are vending machines. Restrooms are also available.
Quintessa Hotel - Osaka Bay. The main reason we chose this hotel was its proximity to the Osaka Nanko Bird Sanctuary. We highly recommend this hotel. The staff are very nice and helpful. The rooms huge and the amenities are plentiful. We only tried the in house restaurant, Aimable, once, for their breakfast buffet. Service was excellent and there was a great variety of food.
Throughout our stay, we used the local commuter trains. They were fast and efficient. The people at the information booth were very helpful and even accompanied us at the ticketing machines to show us how to operate them.
We did use a taxi once from the hotel to the bird sanctuary and I must say it was quite expensive: 1200 yen (about $11) for a little more than a kilometer's drive.
We are budgetarians when it comes to dining. Most of our breakfast/dinner items were bought from the convenience stores such as Lawson's, 7-11, or Family Mart.
We did visit the downtown area and had lunch at the popular tourist spots such as Dontonburi Food Hall Blast where we had Mexican fare at Chronic Tacos, and at Kuromon-Ichiba Market where we enjoyed authentic Japanese food.
One of the places we tried was the popular Mos Burger at the ATC Mall which is also within walking distance from our hotel.
Another place we had lunch at the ATC Mall was Don Don Tei which is basically a fast food restaurant. Their rice toppings are very delicious!