MH 1138?? That is the KUL-PEN Malaysia domestic flight that leaves in the morning.
And NH815 is the NRT-KUL ANA fight! arrives in the evening
So, are you talking about a tight connection at Kuala Lumpur?
the flight numbers above imply an overnight connection at KUL (arrive on NH815 in the evening, leave on MH1138 early next day)
Hope you havent mixed up the flight numbers and dates.

the KUL airport international and domestic flights fly out from different terminals, and terminals are not well connected.
You will definitely not make the connection at KUL.
This question is better asked in the Malaysia forum. (if the flight numbers you provided are correct)