The stories and heroines are completely separate for each protagonist.

Kashiwaba Yuki arc:
The season is late fall and the tomefure girls are still staying at Yuki's house.
One day, Sakurako came up with an idea to go to the Halloween event hosted at a famous theme park. Everyone else protested, as they had no way of getting tickets on such a quick notice, but then Sayaka pulled something out of her bag...

Takamine Yuuji arc:
Christmas has already passed with the New Year just around the corner, and Yuuji is eating lunch home alone. He had been living with the tomefure girls for a long time, but they all decided to go back home for the holidays. It's been a long time since he lived on his own. As he was thinking about how to spend New Year's Eve, something happened...

[Translated from the official site.]