After days of searching online I am finally sure that these are the recommended spark plus for Mira E:S engine:
NGK Iridium SILKR6D10G (FactoryInstalled)
NGK IridiumMax LKR6AIX-P
Denso Iridium Power IXUH20I
Denso Iridium Tough VXUH20I
BOSCH Double Iridium YR7MII33X
But now the problem is that I need to find out where to buy from. Any leads?