He asked her out on this date didn't he? There. Dating.
I get it though. Japanese are big on the kokuhaku thing. As a westerner, I find it odd though. Dating as an adult in the west, there's no formal proposal of "going out." You ask someone out on a date. If you enjoy it, you ask again. Repeat. The part about being bf/gf or dating exclusively naturally develops over time or it doesn't.
It's kinda like the difference between formally requesting permission to kiss, or just kinda leaning in, reading body language, understanding each other's feelings about it without saying a word, and it happens or it doesn't without the need for a discussion first.
Similarly, when was the last time you formally asked someone to be your friend? If you did you'd seem like a child. That's kinda how the kokuhaku confession feels, childish. Endearing when you see kids do it, but they continue that right into adult dating in Japan.
Considering how the Japanese culture is otherwise very non-vocal about feelings and things, I find it kinda fascinating that we're reversed on this one.