「宇宙から来た強調構文」です。
Taichou met Musume at Shibuya yesterday.
It was yesterday that Taichou met Musume at Shibuya.
It was at Shibuya that Taichou met Musume yesterday.
It was Taichou that met Musume at Shibuya yesterday.
It was Musume that Taichou met at Shibuya yesterday.