Why does the Japanese Army (IJA) commit atrocities during WW2?

I heard through many documentaries, encyclopedia and Quora that the Japanese during World War 2 have committed atrocities. However, I never hear the main reasons and also heard that it is usually the smaller officers who committed atrocities.

I asked Quora but they didn’t give me an answer and also blaming other countries for other atrocities. I heard this website and adding details explaining the question background makes me want to use the website.

So what is the reasons of the question I asked?