I did wonder about the plural way before the main game even began when pictoshark referred to “wielders of red in this domain”. Who else but Restkastel could have been the second person with that authority?
Anyhow, time to contribute something for the cause. Karifean and Antra seem to be taking the “one of the fellow employees is the culprit” -approach, so I suppose I should try something different.
There’s a person on the boat who is not an employee of the design company nor a member of the boat staff. That person, referred to as the assassin, is the culprit. By the time the clock struck 24:00 on the first day, the assassin had already killed one of the employees and thrown him off the boat. Later that night, the assassin attacked the victim. The assassin gained access to the victim’s room by stealing a key or picking the lock. Likewise, the knife the assassin used was stolen.
As for why the assassin’s attack failed so miserably… perhaps he was incompetent. Or some unforeseen circumstance such as a potential witness forced him to leave mid-stabbery. Perhaps the room was pitch black and he assumed the victim was sleeping in his bed the other way around, intending to stab his chest but stabbing his legs instead. Perhaps the assassin suffered from some kind of medical condition and had a fit that forced him to interrupt the murder.
There’s an alternate theory, though. There were two “victims” of that incident. The assassin successfully killed his target - victim A - in “the victim’s room”, and disposed of the body, perhaps through a window. Then, the assassin, for some reason, took victim A’s place and went to sleep on his bed, later stabbing himself, making himself the victim B, and calling the first aid staff to help him. All red truths referring to “the victim” could refer to either victim A or victim B, meaning that it is possible to interpret the reds referring to the victim in a way that does not contradict with this theory.
As for why the assassin would go to such lengths for such a charade, he did it to make the staff think that the bloodstains from the murder were from an accident and thus remain unaware that anyone had been murdered. Since the staff of the boat do not necessarily recognize the employees of the company, the assassin could pretend to be an employee. Naturally, this deception would never go unnoticed by the other employees, but they were in on the plan. They might have done absolutely nothing to actually help the stabbing, but they could cooperate to cover up the murder(s). The first murder performed by the assassin could be dismissed as a tragic accident if there was nothing to indicate the victim didn’t just fall off the boat on his own.
