At the end of Nijigahara Holograph (Rainbow Field Holograph), Amahiko meets an old man at the hospital who gives him the box he carried around for the whole manga containing "a spell". The old man then asks Amahiko what his name is and tells him he is called Amahiko too, just before turning into a butterfly (or so it seems from the last scene):
However in the whole story there isn't any other character named Amahiko so I'm confused about who the old man is, also because I've read various theories on different websites.
The old man and Amahiko could be the same person, however this would create a loop since Amahiko (old version) would give the magic box to himself (young version) and wouldn't really explain why does he seem to turn into a butterfly.
Another interesting theory is that the old man is God (or some kind of supernatural being) who came on earth to encourage Amahiko who was kind of depressed and didn't want to stand up and recover from the fall, this is supported by the fact that he seems to know a lot about Amahiko (however this is also a good point for the first theory), his face is never shown clearly and he just disappears/turns into a butterfly (and the butterflies have a lot of supernatural meanings in this manga).
There's also the possibility that Amahiko, being lost in his own world, imagined the old man, but he is shown talking to another character at the beginning of the manga so I don't think this is the case.
So, my question is, who is this old man? And whoever he is, what does this character mean/represent? What does the magic box represent since it isn't actually opened by Amahiko?
I really like this manga, but there are so many details I need to clear up a bit!