Future null singularity due to gravitational collapse

In the case of unhindered gravitational collapse of a matter cloud governed by the Lemaître-Tolman-Bondi (LTB) spacetime, the end-state singularity is either locally visible, globally visible, or completely hidden. We have a past null singularity in the first two cases while a future spacelike singularity in the last case. Here, we show an example of a gravitational collapse model whose end state is a future null singularity (it has a causal property that is unlike the cases involving LTB spacetime). We depict such a distinct causal structure of the singularity by conformal diagrams.