Japanese war crimes are in the past. They are real and significant. You could claim the apologies Japan offered to China are undermined by incidents of nationalists denying the crimes(compare to Germany's apologies which are often considered to be among the better ones) or the reparations offered were not enough(china turned them down). I think that can be debated. But Japan isn't doing anything today.

Japan is for all of its faults a liberal democratic country with no interest in conquering anyone. China is an authoritarian dictatorship getting worse (under the later years of Xi) and threatening imperialist actions especially against the independent nation of Taiwan(some parallels to Russia getting worse under later years of Putin and starting an imperialist war against Ukraine).