There is only ONE international school in Osaka offering K12 education.
If you want to explore more schools, you can check out International schools in Kobe. There are many people working in Osaka and living in Kobe for the sake of school and other reasons like proximity to their community. And Vice versa.
Click the below school name(s) to get the details of the international school.
There were 2 international schools which got merged into one.
Senri & Osaka International school of Kwansei Gakuin
Mino City, Osaka