I can't think of an idiom off-hand, or a proverb which conveys the same delicacy of meaning as the Japanese “die on a tatami mat”. The nearest I came up with are: to die at home and to die peacefully.
The phrase to die at home expresses the desire to die in one's home surrounded (possibly) by family and friends, in the comfort of one's own bed. It is the idea of dying alone, without dignity, in a strange room, i.e. a hospital ward, and with strangers caring for you that many dying people wish to avoid.
When asked where they want to die, most people of all ages would prefer to die at home; in one study, over three times as many elderly wanted to die at home as wanted to die in a hospital (Kalish and Reynolds, 1976).
The second phrase, to die peacefully expresses the wish to die painlessly. Many will also say: I want to die peacefully in my sleep.
"All I want is for my mother to die peacefully here at home."
The phrase was used at King George V's death in 1952
His Majesty, King George VI, has died peacefully in his sleep at Sandringham House.
The top concern of the dying is that they do not want to be in pain – then that they do not want to be a burden and thirdly, that they do not want to be alone. The first and last of those are sometimes hard to achieve
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