(from ebookjapan):
Yumi's proud older sister, Yoko, is chosen to play the lead role in the ballet company's performance of Swan Lake. However, just before the performance, Yoko receives a strange threatening letter, and when she disobeys the letter, she is turned into a swan as per the threat! A science fiction mystery inspired by the ballet masterpiece, "Swan Lake"! The other is "Yesterday Won't Come Again, But Tomorrow Also...", a story about a mysterious girl and Kenji who grows every day as they meet each other. The Girl with the Golden Eyes," about a girl who appears in a snowstorm at a mountain cottage. Contains three stories in total.

Note: CDJapan link only for second oneshot "Yesterday Won't Come Again, But Tomorrow Also...", included with other oneshots from different Ishinomori shojo one-shot compilations.