How long of a layover do I need in NRT?

I'm looking at a flight from ATL to SIN connecting in NRT in August.

Matrix shows a 1:55 min layover. Is that enough time? Both flights appear to be Delta Metal (DL 295 to DL 621). I would be traveling business class.

I haven't connected internationally very often. Will I need to clear customs in Tokyo? What processing delays should I expect?

Appreciate the help in advance. Just trying to decide if this connection is really workable.

Thanks in advance.