Kaisen don is becoming more popular lately. Many izakaya which is a Japanese-style pub serves kaisen don for lunch. Kaisen don is a kind of rice bowl dish. Raw fish is sliced and put on top of the rice. We usually eat it after mixing wasabi with soy sauce as shown in the pictures. I found a reasonable seafood restaurant which serves delicious kaisen don near JR Osaka station. The restaurant is called Hamayaki Doragon (https://tabelog.com/en/osaka/A2701/A270101/27107226/), it is located at Osaka 3rd building. Since there are many affordable restaurants in Osaka 1st, 2nd, 3rd building, you should try and have lunch in these area. The kaisen don costs 880 yen including consumption tax. The ingredients are salmon, tuna, greater amberjack and minced tuna.
Related post : https://www.enjoykansailife.com/blog/kaisen-don