create alias aikatsu -> aikatsu!

Link to alias

Worthwhile alias to have, in case anyone forgets the title has an exclamation.

Done

create implication aikatsu_stars! -> aikatsu!

Link to request

Like this, so we need aikatsu!_(series) tag (guess it's too early for now).
There is also aikatsu!_photo_on_stage!!, but low post count and all from one user, so I don't think implication is needed.

The bulk update request #877 has been approved.