Kurushima works for the Thanatology dpt, carrying out illegal euthanasia (after investigating the client - for not getting into legal trouble) to give those who desire a peaceful death.
ch.1-2 client: a lung cancer afflicted man (looks like a former high-ranking exec) whose sole caretaker is his now tired wife (who liked teaching tea ceremony).
LR ch.2
Thanatos no Shisha