Itsudatte My Santa!
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This is a two-episode OVA that was released in Japan in December 2005. According to Wikipedia, it was "scheduled" to be released in the US in 2007, but was recalled because its rating was misprinted as "TV-PG" instead of "TV-MA." Well... I don't remember when I first heard of it, but I'm fairly sure I wanted to see it for at least a few years, unaware of the recall, and had it on my Amazon wish list. I received it as a gift for Christmas in 2016, and got around to watching it on Christmas 2017. So... apparently not all copies were actually returned to FUNimation. (My copy does indeed say "TV-PG," and I'd definitely agree that it should be "TV-MA.")

So, um... there's this teenager named Santa, who was given that name because he was born on Christmas Eve. (So I guess to all you folks who lament having been born on or around Christmas, always remember it could be worse.) Because of this, he hates Christmas, but more importantly, he hates it because his parents are always traveling for their work, which means Santa never gets to see them. And of course that's hardest for him at Christmas, because they're missing both the holiday and his birthday. Anyway, one year on his birthday, he meets a very strange girl named Mai, who claims to be a Santa Claus in training. This means she has some magical powers, but they're weirdly specific (I won't try to explain that). And she hasn't got as many powers as she could have, once she completes her training. Although she also has to help Santa be happy in order to increase her power. But he's not interested in her help, at least not at first. Eventually he agrees to spend the night with her- but not like that! And um, I dunno. It's all just incredibly weird. And Mai immediately falls in love with Santa, for no apparent reason. I get the impression that the entire thing is meant to be an over-the-top parody of typical anime weirdness.

At the end of the first episode, there's a preview of the next one, which is set six months later. It starts out in the summer, at the beach, and I think Santa and Mai are meant to be a couple, at that point. It's clear that they've gotten to know each other a lot better over the past six months, but we really aren't given any idea of any of the stuff that has happened to them, or between them. Then a girl named Sharry shows up, who is another Santa Claus in training. She's at a much higher level than Mai, despite being the same age. And they have a fierce rivalry, but we eventually learn they're also best friends. And a little girl named MaiMai shows up, who is Mai's younger sister. (She doesn't ever say much, but I found whatever few words she did have amusing.) Anyway, Sharry had been assigned to take over Mai's mission, apparently, which meant Mai would have to return to school and possibly never see Santa again. But she has six months before she has to leave, so we see a few brief scenes over the rest of the summer, fall, and finally up to Christmas, again. In all that time, she wants to say goodbye to Santa, but she can't even bring himself to tell him she's leaving. But of course she finally does have a heartfelt goodbye, at the last minute... and then there's a twist ending, which I won't spoil.

There's also a preview of the third episode, which I think would have been really fun to see, but of course it was all a joke, there was never any intention of actually making another episode. Anyway... I dunno what else to tell you, except that there is some comical fanservice (hence the need for an MA rating). And um, the whole story (or stories) can really only be enjoyed if you have a very high tolerance for redonkulousness. (I'd also suggest drinking while you watch it.) But I thought it was fun.