Zero no Mono / Toy of Darkness

The hentai is based on the eponymous manga released in 1999.

The main character killed his free time as best he could. He tried to escape the boring and gray everyday life. At university, he always imagined having sex with various female students right during lectures. He saw himself as a cool macho without flaws. One night he meets an incredibly beautiful girl with blue hair and an eye patch. He rushes after her like a stalker and ends up in her apartment, where complete madness reigned - in different corners of the room, masked men were having sex with super beauties. And that blue-haired girl obviously ran everything. She approached our hero and without further ado began to undress him...