To me personally This one of the greatest hentai i ever watched. The girls are beatiful, sexy and smooth, the dress are beautiful. But don't expect the same quality with the likes of Sora no ir, mizu no iro though. there is the occassional poorly drawn limbs and nad detail. But it is tolerable.
The girls have different body, for example , Saki has bigger boobs and more visible abdomen muscles than the petit bodied yukari. the rapes are dehumanizing. and cry is pretty is convincing
But those who have watched this hentai this a bad and low quality one, here are the possible reasons
The producer made a grave error by thinking that he is making a mystery anime. The characters are very stupid numbskulls. They were trapped in a big mansion and knew someone is out to kill them, but instead of trying to break out or staying together they foolishly split up. And the lead man Akira , all he could do was running around and cry when his friend is in trouble. it's pretty annoying. I recommend you watch the english dub, eventhough some said the dialog had stupid crappy porn jokes, at least Akira sounds more manly and it give him dignity.
i don't want to give a spoiler, but believe the reason why it all happened was stupid beyond comprehension.
- the sex scenes are very shortin ep 1. Yukari'rs rape was stopped when it started to get fun and it last less than one and a half minute. Saki's rape lasted longer about 3:06 minutes -unfortunately minutes took up by dialogues-, and it was hotter. but we wanted longer sex scenes and more sex positions. and these two kinda faded away on the second episode