afterworld; the world after death
A straightforward loanword referring to the realm or state of existence after death, similar to 'afterlife'.
その小説はアフターワールドを舞台にしている。
The novel is set in the afterworld.
来世 is a more traditional Buddhist/Japanese term for the next world or afterlife, while アフターワールド is a modern, often fictional or Western-influenced loanword.
死後の世界 is a descriptive phrase meaning 'the world after death', more common in everyday speech than the loanword アフターワールド.
Borrowed from English 'afterworld'.