I can tell you that is most certainly not true and that everyone was treated in a terrible fashion. I suppose if you want to nitpick you could make claims that the Asian populace was treated worse in some very extreme instances such as Unit 731 which unleashed the bubonic plague on their test subjects. But that would not be very nuanced and I think even bordering on disrespectful to suggest that people of European descent were treated better.

The Japanese had plans to enact, at least nominally, the East Asian Co-Prosperity Sphere which in their propaganda to other Asian peoples was supposedly a Japanese led and sponsored bloc/alliance of independent Asian states free from Western colonial influence. This of course was largely a sham and it was essentially the Japanese replacing the Europeans as their effective colonial masters in all except name. The Japanese Co-Prosperity sphere was effectively their sphere of influence where they gave some of their captured territories nominal independence and retained actual control to exploit the resources for the war effort.

You are correct to say that the local people endured some very harsh treatment and suffered numerous atrocities such as the Rape of Nanking and the Sook Ching Massacre of the local Chinese population in Singapore just to name a few. The Japanese most definitely have a fervent anti-Chinese agenda both fuelled by propaganda and the growing rate of attrition in their war with them. However they actually treated indigenous and non-chinese populations in South East Asian relatively better, although it was still much worse than being under the colonial administration. The Japanese sponsored the Indian National Army which was largely comprised of former sepoys and even officers from the British Indian Army. To them, the Indians were not necessarily the enemy and a potential tool to be used against the British and for propaganda purposes. The Army was largely used as a tool to stoke the nationalist flames in Indian and hopefully sow discontent in the British Indian Army and in the Raj itself to reduce their warfighting capability. Thus many captured Indians were encouraged to turn traitor and were given preferential treatment relative to the Chinese where innocent civilians that were never combatants were being rounded up for execution.

It was also much better to be a non-Chinese/non-European civilian as they were not systematically interned if they were a male of fighting age and were generally not harassed without provocation. There were many instances where the local population would actually collaborate with the Japanese and benefitted. One notable example would be Joshua Benjamin Jeyaretnam a future Singapore politician who worked with the Japanese as a clerk and translator and thus avoided the worse of the occupation. For those less privileged such as him, it would also be an opportunity to get formal schooling which was sponsored by the Japanese to create future local adminstrators and loyalist for their new possesions. J.B Jeyaretnam's memoirs can be found here and are an excellent primary source detailing how the locals actually managed to benefit from the occupation.

Your assumption that Europeans were treated better is also not so well founded. There were numerous massacres of British troops during the Malayan Campaign with notable events such as the Parit Sulong Massacre where the British POWs taken by the Japanese were burnt alive, physically mutilated and repeatedly run over by vehicles. During the Fall of Singapore there was also the Alexandria Military Hospital Massacre where the wounded were executed which also included white female nurses. Both of which are recounted in Colin Smith's Singapore Burning which he retells in gruesome detail from a consolidation of primary sources. European POWs were also sent to work on the Railway of Death in Thaliand and Burma where many were worked to death in terrible conditions. Outside the British Army, the American POW also suffered inhumane treatment during the notorious Bataan Death March. By the end of the war, the failing food supplies for even the Japanese themselves led the to European POWs suffering from malnutrition appearing as husk of their former selves when they were finally liberated, for those that managed to survive at least.

In conclusion, both Europeans and Asians suffered terribly and it's not fair to generalize and group all Asians together and label their treatment as the same. If you really wish to draw a distinction, the Chinese had it worse of all since they were systematically executed which would easily be worse than being a European POW with at least a chance at survival or a civilian that had to suffer the occupation.