placing a body in a coffin, encoffining
納棺ってね昔は家族でやってたものなの
You know, in the old days, families used to prepare the deceased for burial themselves.
— Departures (2008)
“納棺”って?
What does “nōkan” mean?
— ほんとうのピノッキオ (2019)
納棺
placing the deceased in the coffin
呼ばれたからには納棺しないといけない
Now that I've been called in, I have to put the body in the coffin.
だからNKは納棺のNK
So NK is the NK in nōkan—the act of placing a body in a coffin.