I just wanted to mention the ending, after the credits, because the English subs make no sense so I switched to Korean which has the same sentence structure with Japanese to get it (verb comes last after subject/object)

Loosely translated, he basically types "We became adults couldn't" meaning we couldn't become adults, the title of the movie and how we go in to watching it from the start. And deletes the last part which leaves the sentence as "We became adults". Which I suppose explains its lack of closure and anticlimactic finale. Adult life is boring and ordinary, right!? That's how I interpret it at least.