Page 21 is the most "hardcore" page in this doujinshi, and it really isn't hentai. It is ecchi in today's terms. Now, if this was e-hentai back in 1994 when the doujin was made, then okay, an argument could be made for hentai. But for now, this is a "NON-H" doujinshi so it should remain classed in the "NON-H" category.