Tagged as spoilers due to references to events from the series.

In volume 5, there is a plain black panel where it says "That night, punpun onadera died". Obviously, most people probably see this as just being metaphorical or just a joke, as afterwards he possesses/is possessed by Takashi, his neighbour. However, i have some reasons to think that this is his death.

1. Before this point, he is hopelessly looking for Aiko, and yet as soon as this happens he almost immediately finds her, literally in the span of a few pages.

2. The story begins to take a drastically different turn of events after this point, as it is the part where his life starts moving way faster and he finally runs away with Aiko. This is extremely out of character for him, as before this he was too scared to do literally anything. Obviously, this could be traced to him taking the personality of Takashi, but it still doesn't really make sense considering the character of him that had developed over the series to this point.

3. Similar to point 2, but Punpun radically changes as a whole, becoming absurdly evil, violent and confident, which is a side of him that is almost a comical opposite to the way he was before.

I essentially view volumes 5-7, in this theory, as being what Punpun dreams about in his last moments, where he essentially just delves into his deepest desires (being more confident, Aiko, etc). There are definitely flaws with this theory but I am interested to here other people's perspectives or other theories