The WTO looks at tariffs, not currency manipulation. The Abe government specifically said they were using quantitative easing to boost export markets.
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The WTO absolutely looks at currency manipulation. As does IMF. And Japan has never been found guilty by either. So unless you have proof of guilt, you're talking out your ass. Believing in something without evidence is called "religion" or "fanaticism".
Here's a couple of lines from WTO about currency manipulation:
“Members shall not, by exchange action, frustrate the intent of the provisions of this Agreement."
“Multiple currency practices can in certain circumstances constitute a subsidy to exports which may be met by countervailing duties."
"Prohibited export subsidies include “currency retention schemes” and the provision by governments “of exchange risk programs.”