This is one part of Japan not many talk about. But there are many businesses serving adult entertainment (red light) in Japan. I do not know if this topic is suited to Japamese-Online or not.
Since 1996, Japanese-Online has been provided as a free service from PSPinc with the purpose of providing resources to individuals interested in learning about the Japanese Language and culture.
Japanese-Online has content suited to varying levels of study, including lessons for beginners as well as lessons tailored for those who need grammar and writing resources. Lessons are best suited to those who have basic understanding of hiragana and katakana alphabets before moving on to the more advanced grammar and particle lessons. Grammar lessons focus on learning about writing and creating more complex sentences and most lessons will not use romaji (Japanese sounds written with roman letters). Kanji is used in the lessons with hiragana and English translations provided.