Pink and Gray (2016)

Male leads in both productions have to cope with death of their best friend. Both Ao to Boku and Pink and Gray are aesthetically pleasing and feature some kind of plot twist

Both stories are psychological character studies that centre around the relationship of two actors.
They depict their friendship, interdependence, jealousy, conflicts, distancing and reconciliation.

it's not that they're that similar - completely different you may say, but there's a similarity (hard to grasp similarity that I personally feel in there) and if I said what I think that is, it'd be spoilers ... that kind of thing
somehow, I'm sorry, but I still recommend each to go after the other
..especially if you've seen neither

Its not that much the same but the theme is quite close as well as the depth of both movies. Both revolves around fame and the dark side of it. Equally intriguing and beautiful.

Both are fucked up and quite graphic. Both also deals with the loss of a friend and the cause itself.

both movies were directed by the same person, have a similar feel and dont look like your typical movie (Pink and Grey's second half is mostly shot in black and white, River's Edge has interviews of the characters sprinkled inbetween and also 4:3 format). Also the characters tend to be kind of fucked up.