Traditional way as in everyone uses pink penlights during the last MC/Grad ceremony. It's not official yet, though.
They were discussing about this. When to use it, should we use more than one colour, should we use something else too and not just penlights, etc. I kinda liked the idea of using pink penlights from the first second of the concert to the last, but oh well...
And, yeah, pink was used before in Tsujikago's grad. I heard that some Rika fans objected that at that time. But they don't care if it's already used or not. How can you use any other colour in Rika's grad anyway?