Sorry if this has already been mentioned, but
with these two drawings by Mr. Fujimoto, the movie newly drawn illustrations, if you look closely, the backgrounds are the same place, right?
And, in the first one with the school uniform and bare face, the background has low leaves behind, while in the second one with Denji, it's overgrown,
if we assume the timeline is straight from the first to the second,
could this be that the first one is actually Reze who's currently studying as a student somewhere, and then afterward, it's a metaphor for DenReze reuniting like in the second one...? Clothing-wise too, the left seems like a cold period and the right a warm period, so..