It has come to Celestia's attention that a certain sister of hers has become rather saddened as of recently. As much as she would enjoy dealing with the matter personally, she does indeed have royal duties to attend to.

That doesn't mean she can't get somepony else to help cheer up her beloved sister. She will call upon the only pony she knows can successfully pull off such a delicate operation. Ponyville's own Pinkamena Diane "Responsibility" Pie.