Twin Star Exorcists was not well-received during its simulcast, part of the reason was down to studio Pierrot who are known for butchering anime adaptations and adding pointless filler. The anime being 50 episodes long and split into four parts can put off buyers especially at the asking price. Another reason I reckon is down to Anime Limited's handling of the series - a box for all four parts is perfectly fine by all means, however adding booklets for parts two to four I felt was more of a case of trying to ramp up the price when the show doesn't have much value to begin with. I feel this was a big misstep for the distributor. Like booklets are great and all, but sometimes it's worth taking a step back and think to yourself whether this show or release really warranted it. At this rate, it's probably their biggest flop since Samurai Flamenco.I wonder why they didn't sell well, could it be the length of time between parts, maybe? I don't know many who would wait 8 months beetween part one and two, so could the fault for the low sales be AL themselves?
Note: This is just my opinion on the matter.