When Dr Tenma visits a comatose Johan in hospital, we see a scene where Johan wakes up from coma to ask an existential question, which contrasts with this philosophy that life is inherently meaningless. Tenma does not answer; we cut to a scene where Tenma is panting in a cold sweat over a comatose Johan.
Which of these interpretations is true:
- Tenma has hallucinated it entirely and Johan has never gained a conscious state, much less walked away.
- Johan has indeed woken up and questioned Tenma and later escaped.
- The screenwriter (or manga artist) has made this a perfect ambiguity.
The scene seems open to interpretation as I later discovered. The contrasting interpretations:
- I infer that Tenma hallucinated this entirely as in the next scene Johan appears to not have ever stirred. Tenma feels safe leaving him alone. Tenma hallucinated this, overcome by understanding the reason for Johan's bitter life philosophy.
- Popular Wikia author (quoted below) says that there is a possibility that it's for real (Johan woke up, questioned Tenma, went back to sleep while Tenma was in a cold sweat, then later left the building). This is supported by the fact that Johan leaves his bed by escape (or death; as the same article presents this ambiguity), proving that he was physically capable of doing so.
...end of the series, Tenma paid Johan a visit in the state police hospital, where he had been unconscious ever since the massacre. After being informed that he had [a] name, Johan sat up and began talking to Tenma, retelling the story of his mother's choice and asking which child wasn't needed. It is unclear whether this was a hallucination that Tenma experienced or if it was actually real.
His mother's true sentiments while making the switch might have been frightening for Johan, leaving him to question the scene for years to come. However, if that segment is to be interpreted as a hallucination by Tenma, this might not be the case.