Just saying. The Yen Press translation is pretty bad. People saved epubs and pdfs of fan translations which were so much better. Just go look for them.
Although only up to vol.4 has been officially translated, you can find a couple more out there in the internet (fan-translated)... However, none of us can help you with that, although a couple of us should know where to find them, we can not tell you in case the site gets DMCA'd or something.
well... volume 4 i would guess? but the ending in the anime is original of only the anime, what happened at the end was made up