Killing Conjoined Twins using Death Note There are Mr. A and Mr. B. They are conjoined twins who each has their own set of organs except for the heart. I write the name of Mr. A while imagining his face, with the cause of death being falling from the top of Tokyo Tower head first. Let's say the difference in height between the two is less than 1 cm. Will Mr. B also die?

According to How to Use: XXVI, item 2:


  Even though only one name is written in the Death Note, if it influences and causes other humans that are not written in it to die, the victim's cause of death will be a heart attack.


However, a heart attack will also kill Mr. B.

Additionally, How to Use: X, item 2 stated:


  Whether the cause of the individual's death is either a suicide or accident, if the death leads to the death of more than the intended, the person will simply die of a heart attack. This is to ensure that other lives are not influenced.




This question is a bit different than the one proposed as possible duplicate. In the proposed question, the death of the pilot or the surgeon doesn't necessarily means that the people in the plane or the one in the surgery will 100% die. There is a delay before they actually die. Surgery is rarely done by only one doctor. It usually is done by a team of doctors, so the other doctors can still save the patient. Flying a plane is also the same. There is also the co-pilot. In the case of my question, killing Mr. A is the same as killing Mr. B since they share the same heart with no delay whatsoever to save Mr. B.
Even though only one name is written in the Death Note, if it influences and causes other humans that are not written in it to die, the victim's cause of death will be a heart attack.


Does rule XXVI not answer your question? Mathematically speaking you could rewrite it as follows.


  Causes others to die => (Cause = Heart-attack).


Here you could see that the heart attack would be logically implied as the cause of death if others are influenced, regardless whether they take others with them. Therefore they would both die. Mr. B would also be killed. Remember that this rule does not say that if you would cause another human to die, that you would stay alive. It only says that the cause changes to a heart attack, which in this case would kill both, so the death of the other would be unavoidable in this case.

If this would not have been true, Light would have been able to make himself completely immune to the Death Note, even making it impossible for Ryuk to kill him. Light could have implanted a bomb inside a few people, that would all be triggered when either his heart or their heart stopped beating. He would repeat this over different groups of people. By doing so, Ryuk would be rendered unable to kill Light as it would be impossible to kill any of those with a bomb implanted, as it would kill the others and he would not be able to kill Light as it would kill all of them. This would make Light immune to the Death Note, which I found very unlikely to be true, because it would completely contradict the first and most fundamental rule of the Death Note namely


  The human whose name is written in this note shall die.