My guess is Japan won't complain much unless the fuel spill impacts a special tuna or another sacred species. If the cruiser burns the fuel I think it does (jet or very close to it), the stuff'll probably dissipate.
But I see a couple "political" issues:
First, a grounding is nearly always a career ender, regardless of cause. Like "shouldn't've dragged in the first case" or "should have anticipated a propulsion casualty."
Second will fuel (sorry for somewhat of a pun...) the discussion wanting to decommission this whole class as "too old" and "maintenance money pit." Now they can add "accident prone" and "unreliable."
I hope we can follow the news.