Misaki and Usui just existing in the same room, doing nothing particularly important, is enough because by this point you've earned the right to want them together without plot permission. The birthday date setup promises romance then pivots to pure character comedy instead, which stings in exactly the way long-series fans deserve. This is what the show knows about itself: the relationship IS the story, not the destination of one.
Misaki Ayuzawa comes home from her part-time job at Maid Latte with her maid uniform torn, damaged by accident while she was shifting potted plants. She asks her mother to sew it up, but her younger sister Suzuna offers to do the job and has it fixed in no time. Suzuna then wants to try the outfit on herself, much to Misaki's alarm. While Misaki works to keep things from getting more embarrassing, visitors she was not expecting turn up at the house. This one-episode comedy extra was bundled with the tenth Blu-ray and DVD volume.