i don't know about jfk-nrt, but have had these seats twice from us to argentina...the first time, it seemed to be slanted, but wonderful....

the second time, i felt flat after playing w/the buttons....had a pillow and blanket....worked fine for me at 6 foot 3....

enjoy....

edit to add...

i never had a company trip to japan, but others that did said, don't sweat it, you can get drunk twice on the flight...