Kaya, Nene's younger sister, comes back after a very long time to fulfill an anniversary that only comes around once every 449 years when a certain comet makes its closest approach to Earth. Kaya continuously bother Nene throughout the day because she wants to be close to her, but since Nene has work to do, she shuns Kaya's advances. Later when Tōka is looking through the telescope to view the comet, he does not see the stars but instead views a hide and seek game played 1347 years ago between Nene and Kaya.