Yang Yi was on a large cruise ship.
The old man Yang Yi was disguised as wasn't using a fake identity; he only realized when he boarded that he had replaced a real elderly man who was supposed to board the ship.
The reason Kate needed such a long time to disguise Yang Yi was to ensure he looked exactly like the real elderly man.
He was actually a very ordinary elderly man who had been widowed for a year and a half. Living alone, having a lot of savings, and feeling bored, he booked a spot on a luxury cruise.
He booked the spot two months in advance. It wasn't the most expensive cabin, but it was still an excellent one on the ship.
The Black Devil needed to board the ship first to check for that kind of white box, but there wasn't any because such a white box, not being a standard device, would never be placed on a cruise ship with such low timeliness.
