Hentai Express is basically evil rape train vs sex powered mechs. The story is pretty bad, even by hentai standards, with some tentacle spewing train that is powered by women orgasming inside that needs to be taken down by a team of mech pilots that also power their machines by having orgasms. The train makes no sense as to why exists, what the purpose of it is, and why the villain is doing this. The mech also doesn't make much sense as it basically autopilots as the girl just orgasms inside it. Overall the story is bland with bad action scenes with no ending. The artis pretty solid though with decent animation as well. The girls look great and have a similar style to Angel Blade. The main villain however is a bit of the ugly bastard type which knocks it down a little in the enjoyment aspect as he is continuously shown having sex or just sitting around naked.

Overall it's an okay hentai with good art but horrible story. If you just want some tentacle rape or girls masturbating in mechs you might enjoy this one, but other than that its pretty forgettable and not really recommend worthy.