On Ubuntu/Mac, that's very easy, so omitted For Windows, see my blog post How to install Python2 and Python3 on Windows
For Mac pip3 installed as default, see pip3 macos For Ubuntu, TODO For Windows, TODO Then
pip3 install -r requirements.txt
ehentai -u https://e-hentai.org/g/1178073/30bc24b00a/
Or
ehentai --url=https://e-hentai.org/g/1178073/30bc24b00a/
This code is only for fun and tech sharing, any illegal use is depricated, if you disobey the law in your Country/Region when using this code, the author takes no responsibilites for that.