Good concept, poor implementation. The initial "foursome" isn't actually a foursome, just three sex scenes in a row. Problem is, none of the three defloration scenes have nakadashi, and it's not sex if you don't cum inside, so they don't even count.

Aside from that, there is an imbalance of sexual content... in particular, Ameri has notably fewer sex scenes than the other heroines. There's also a lot of reused content, such as showing the exact same CG for three separate H-scenes, which is kinda lazy design. And one of the reused scenes is a condom sex. Condoms have no place in H-scenes, since they prevent proper sex by not letting you cum inside.

If every heroine had roughly the same amount of sex scenes, and every sex scene had a nakadashi option, then this would be better. Still, it could be much worse. The teacher/students romance is a great concept, and they did okay with it, although they could have done better. And it has a harem route, which most H-games sadly lack. So it's not terrible, just not great.