Imei Service Details - Japan AU KDDI - iP 6s/6s+/SE/7/7+/8/8+/X/Xr/Xs/XsMax/11/11P/11PM - Source B

U CAN CHECK IF YOUR IMEI IS ELIGIBLE IN THIS SERVICE 

1500# Japan KDDI Unlock Eligibility Check By (IMEI)

NEED IMEI1 ONLY. DON'T SUBMIT IMEI2

https://my.au.com/cmn/WCV009001/WCE009001.hc

if it shows O, then supported 100%

if it shows △, then phone must be activated over 101 days

if it shows ×, then not supported

 

If you do not know how to check, just submit imei, if not supported will reject and refund.