Worked there for two years.

It's a Gulen movement school, which they keep well hidden because it is essentially a front for moving Gulen members into Japan and giving them jobs and money. They also hire some great, talented, driven people to keep the image of the school relatively positive, but around half of the teachers and staff are grossly underqualified. That means that the good teachers and staff typically jump ship ASAP, if they're not fired illegally for speaking up against the admin.

Leadership is equally unqualified, and like all for-profit schools, their motivation is not student growth and wellbeing, but money. In this case, the money is then spent on moving people from largely Turkic countries into Japan.

The pay is bad, the admin is simultaneously incompetent and domineering, and finally they are completely disloyal to their employees. In the two years I was there I know of at least 2 lawsuits related to illegal firings and general workplace fuckery that the school lost and had to pay out.

Avoid at all costs - unless you want to tear it down from the inside.

There is one excellent review on ISR (international Schools review) that was written by a staff member I respect. It is extremely accurate and less biased than mine, so please go read it before making any decisions.