電脳学園４ ～エイプハンターＪ～

In 2006 the people had just one anxiety - "Monkey". Elimination of ozone layer by ultraviolet rays after 1980s caused ape mutation evolution. Mutants were intelligent and since they started to look like humans they secretly infiltrated human society. Thus appeared ape hunters - specialists in identification and "processing" of monkeys.

You are such an ape hunter and you've just received a request from school director to reveal monkeys in the school. The only way to check it is undress the subject and find evidence of his red ass and tail.

[From vndbreview]