Slice loaf to desired thickness and spread one side with Kewpie mayo
Put slices mayo side down into hot pan
Remove slices when toasted & spread other side with Kewpie mayo
Place mayo side down, toasted side up
Add thick (1 - 2cm at least) layer of mixed cheeses
Gently press top bread slice onto cheese, mayo side out
Flip toasty to cook other side
Remove, cut on diagonal, salt, and serve