It's a laugh, but it feels as if it would have been better had it been longer. That's a compliment, really, but you can still feel the difference compared with, say, I Can't Understand What My Husband Is Saying, which is exactly right as it is.
It's based on a four-panel gag manga, obviously. Tomoya (aged 13) acquires a step-sister (Ichika, aged 17) when his father remarries. Unfortunately Ichika's fallen in love with Tomoya. This probably sounds like nightmare fuel and there is indeed plenty of anime that charges terrifyingly into that, but fortunately this show keeps it clean. Tomoya's a child. Ichika's a weirdo, but not a pervert. Her antics, at worst, annoy Tomoya instead of taking the show into 18+ territory. As a result, it's funny.
There's a small amount of very mildly adult material, mind you, but it generally doesn't work and felt a bit tokenistic to me. I like this show, but I'm about to pick at its weak points. One of the girls has big(gish) boobs. Why? Force of anime habit, I think. The show never gets any laughs out of this, although admittedly that's partly because the idea isn't inherently funny. Similarly, Tomoya has a girl-chasing classmate who's as amusing as you'd expect from a girl-chasing anime character, i.e. not in the slightest.
The cast is surprisingly large for such a short show and they even get character development, which is why I say the episodes could have been longer. Most (but not all) of them are in sibling or sibling-like pairs, which provides comic counterpoint to the central gag of the Ichika-Tomoya relationship. The cast includes:
1. TOMOYA-ICHIKA - the show's main "couple", if I can call them that. Ichika drives Tomoya nuts, but despite that they basically get on well. Other characters even comment on it. They're relaxed with each other, if you define the word as "without reserve or inhibition". Tomoya will yell at Ichika as she chases him down the road, etc. They're also both nice people, so they'll be thoughtful towards each other even amid the silliness and they'll immediately apologise if they realise they've gone too far.
2. RURI-KOUKI - the show's most entertaining sibling pair and also technically the only real ones. Tomoya-Ichiya are step-siblings, while Marina-Souichirou are cousins or half-siblings or something. Anyway, Ruri-Ruri is an enthusiastic, friendly girl with just has one minor quirk. She keeps beating up her brother, using wrestling moves and everything.
Meanwhile Kouki is an arrogant son-of-a-bitch who says things like "women are a waste of air" and "your hair sickens me". At first he looks like a comedy hate figure, which is entertaining enough in itself, but then we learn that he's secretly got a sister complex and even a well-hidden nice side. He likes it when his sister assaults him. They both seem to see it as a form of affection and in all other respects have a normal, close sibling relationship. "You've never been struck by the whip of love, you pitiful person."
3. MARINA-SOUICHIROU - fairly minor characters, unless you regard Marina as playing the straight man role. (I'd say that's more often Tomoya.) Marina's buxom and her brother's a nerd. They too get on better than you might expect.
4. FUJISAKI - a pretty bitch who's frequently drawn with a sinister leer and devil wings, but tries to look girlie and mesmerise all the boys. "I'll only show myself in a swimsuit to everyone!" Unfortunately she's the same age as Tomoya, while all the other girls in the cast are seventeen. Tomoya is sweet on her and she's actually quite keen on him, although not exclusively. Interestingly, in later episodes she becomes self-aware and starts trying to tone down her bitchiness, at least around people she regards as friends. By the end of the show, she's more or less become a sympathetic, vulnerable human being.
5. MITSURU - a girl-chasing thirteen-year-old schoolboy who's jealous of everyone else for having hot sisters. Success rate at everything: zero.
That's a pretty good cast. I'd have enjoyed seeing them in 25-minute episodes, not just three-minute ones. Even lesser characters Marina and Mitsuru have potential that could easily have been developed further. Both give us a different angle on the sibling relationship theme. Souichirou in particular only appears in one episode, but the "she has bad taste" comment of Marina's friends afterwards is something I'd quite wanted to see followed up. In three-minute episodes, though, the scope for doing so is limited.
Mind you, the thirteenth OVA episode slows down the pace a bit. We're only talking about four and a half minutes rather than three, but it's still significantly more reflective and less frenetically focused on comedic character interaction. It's a prequel episode, telling Ichika's story from the age of eight to the present day. We get a rare look at Tomoya's parents, including his late mother and something of the feelings of his about-to-remarry father. I liked that episode.
I enjoyed this show. I'd like a second season, but I'd also be keen on seeing it remade in a longer format. Character development is good, but it won't have as much impact as it should when the characters in question have had such a fleeting amount of screen time. I'm not bashing it, though. There are three-minute anime that don't have enough ideas to fill out even that running time. It's funny, it's surprising and I like the cast. It has a theme, even if its treatment of it is often just goofy comedy. I wouldn't call this show brilliant and there's a ton of other anime with basically the same premise, but I'm quite fond of it.
"If I don't hug Tomoya once a day, I start twitching."