Achieving the nirvana you die as a human being psychologically during the life of your body.
Then after only the body dies.
Without achieving nirvana during the life, upon physical death you die physically and psychologically.
This is NOT philosophy its religion.After the death of a person who has attained nirvana, liberation, or perfection, what happens? You do not simply gain non-existence (like the sunyavadis, the worshippers of the void), Gautama Buddha says the experience is unexplainable, Krishna says that you will share his own opulences. But what does that mean, what really happens after you escape from this cycle of birth and rebirth?