Specific PDA in japan

[Aruhi]

Hello!
I'm currently living in Tokyo, and have a Japanese boyfriend that's lived abroad for a majority of his life.
We know full well that PDA in Japan isn't too great, so we never really do a lot of PDA except maybe holding hands while wading through Shibuya crossing and such.
However, I had a question to people more experienced than I am with PDA in Japan.
See, my boyfriend's about a foot taller than I am, so forehead kisses are extremely common between us.
Recently, he's been kissing my forehead subtly (a light brush, mostly) in public. I was just curious as to how forehead kisses are looked upon in public in Japan.

TL;DR: How are forehead kisses looked upon in Japan?

[Chips2014]

Aww that's cute. I don't know what their PDA rules are.