Remove malware on kindle fire?

I think I have malware on my kindle I don't know what it is but I'll try to explain it as best as I can

What the malware does is it loads apps without my consent the apps are in Chinese or Japanese but has some anime girls on them so I assume Japanese and makes my kindle hard to use because they open by themselves and stops my kindle from locking. I last night woke up hearing music coming from my kindle and it was one of the apps so I turn off my kindle. I have formatted it but they still have a way of coming back somehow I even went a day without using it or installed anything so how can I get rid of the malware also at times the kindle gets really slow and unresponsive when the apps are installing themselves

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