International schools NL → Japan. Anyone moved with an 8–9 y/o?

We might move from the Netherlands to Japan for 1–2 years for work, and I’m trying to understand our options for schooling.

Our son is 8 (Dutch school background) and speaks some English, but not fluently. If we choose an international school in Japan, would he struggle too much at this age? Should we wait until his English is stronger?

Because the move would be temporary, we don’t want to interrupt his learning progression or make returning to Dutch school harder.

Has anyone done a similar move with kids around this age?
What were your experiences with international schools in Japan, English support levels, integration, and coming back to NL?

Any advice is appreciated!

by typodsgn