According to the official Twitter account, LocoDol will have a 2nd OVA which will be a Christmas special and would air on Christmas Eve. Miku and Sachika will perform the opening theme.
Also, an all-night event at Cinemart Shinjuku in Tokyo on December 24 will show selected episodes and the OVA, Miku and Sachika will attend the event.
Thanks
Always nice to know Sachika doing something extra