A lot of anime are adaptations of Visual Novel originals. The problem with adapting a VN into a twelve-episode anime is that they almost all are multi-track — work you way through while romancing girl A, then go back and do the same with girl B. The question for an anime studio is, how do we handle this during an adaptation?
One way is to pick one girl and follow her to the end, with all the other girls having walk-on parts. Clannad is a good example. The upside is, the story can devote twelve whole episodes to the budding romance. The downside is is, everyone who likes girl B, or C, or …. will be disappointed.
A second approach, call it the Kanon model, is to keep one girl on the main track, even if it disappears into the background for a bit, and give the other girls their own arcs, without ever promising them romance. This requires a certain skill in balancing the screen time and keeping the main heroine as the obvious favorite.
Finally, we have the omnibus approach, famous in Amagami and Photo Kano, and (this season) Seiren. Each girl gets a turn at romance, and after three or four episodes rides off into the sunset with the protagonist. Then we reset, and go through the whole thing with some new girl. It’s like a collection of short stories instead of a novel. The problem with the omnibus approach is twofold, or maybe three.
First, they are short stories. There’s no depth, no chance to develop characters. The four episodes tend to run to a pattern: boy meets girl; boy and girl hit it off; boy and girl encounter insurmountable relational problems; boy and girl decide to get married.
Second, they use the same cast in different roles across different arcs. It’s kind of an ensemble production — like some of the old Murder, She Wrote programs, where the bad guy one week is an old family friend the next. It’s not just that the main heroine changes, that’s to be expected, it’s that our protagonist’s male friend one arc is a complete stranger the next one. Or maybe they play video games one arc, and the next one he’s off on the soccer team. It makes for a certain mental whiplash.
Finally, and this is a particular problem with Seiren, the protagonist might or might not be the same personality from one arc to the next. In Amagami and Photo Kano, the protagonist was the same person, with the same goals and hangups: in Amagami, he was recovering from having been stood up for a Christmas Date; in Photo Kano he was a camera nut. In each arc we get to see alternative ways he can work through his life problems. In Seiren, he’s a different guy each time.
This season, Seiren is sandwiched in between Tanya the Evil and Demi-chan, and it doesn’t really fill an anime-watching need.