Märchen Paradise

Main character is a high school student who peeked inside a suspiciously looking pipe and got warped into a fairy-tale world.

This work can be considered of the same series as Girls Paradise Rakuen no Tenshi-tachi released a year earlier. The are a lot of fairy-tale heroines featured like Little Red Riding Hood or Snow white. They are all nymphomaniacs, so H scenes are rather bright. It's very easy to get a game over, but frequently saving helps to progress steadily.