It's the 13th OVA episode of the first series of Love, Chunibyo & Other Delusions. I enjoyed it, although of course it helped that I like the show and I'm fond of the characters.
I normally get lazy and include bonus OVA episodes in my review of the main show, but here I'm being good. Such OVAs are independent little beasties. A season will have a story arc, which often won't be improved by having an unrelated one-off OVA plonked afterwards. Quite often, as here, they're not even released in the same year as the main show.
This is a status quo episode, as you'd expect from a bonus OVA, but that's not a neutral statement for this show's heroes. Status quo means a lot of unhealthy-looking behaviour, which an unsympathetic observer could choose to call either delusional or mentally ill. Rikka is living in another world again. Dekomori's once again bouncing off the walls. Everyone else is back to whatever passes for normal... and that's good. Rikka's happy. They're getting on with life, in their respective ways. That's nice to see, after certain developments near the end of the TV series.
The plot: it's Christmas. More than that, it's Japanese Christmas, which means that it's seen as a holiday for romantic couples. Rikka is thus confused, being aware that there's something she sort of wants while also being unable to process it. She tries to talk to Shinka about it, which for Shinka is like trying to gather water in a sieve.
The gang ends up having a Christmas party, which is Christmas-themed enough that this would be quite a nice inclusion in a Christmas anime binge. The girls dress-up. Rikka grapples unsuccessfully with the meaning of it all. "Bloody massacres?" Her relationship with Yuuta develops a little bit, which is nice to see even if there's nothing particularly new being introduced there. It's sweet.
What is new is the episode's angle on Dekomori. Firstly, her house is a palace and her family must be stinking rich. Secondly, the character appears to be developing into a lesbian. (There was one scene that hinted at this in the TV series too, but here it's much more prominent.) As well as her erotic dream about herself and Rikka, there's also an amusing incident with Shinka that's playing with the idea of a romantic coupling of the two girls. (This is funny because Shinka regards Dekomori as a brat who needs swatting like a bug. "I don't want to accept this reality!" She's perpetually annoyed by her and the two are always squabbling. However if you think back to the start of the series, there are similarities between this and Yuuta with Rikka.)
Dekomori also puts a weird pseudo-romantic interpretation on Shinka being grouchy with her and has a go at her for not being bullying enough.
It's nice. I like it. I also approve of a show that's so proud to be celebrating our freedom to be nutters. Next: the movie.