
How do you get the name "Ein" ?! I'm German and that's a number, a number that you do not take as a name ... that's like calling "Come on `one`"
For Koreans it must sound great but it is nonsense. ┑( ̄Д  ̄)┍ ..Sorry.
But the love scenes are beautiful and very intense

Yeah, it did come off as a bit out of place considering how great the author usually is at European names. I'm guessing that both German characters are known by only their surnames to each other which seems really impersonal, even rude. Why hasn't Herr Diesel not been given a first name? Ditto with Herr Ein (Mr One?).

No I dont know theres different varieties in it too. Not just german alone. But can be ancient Germanic too wich do mean "one" yeah, but also "alone" or "unique". Aswell as old Norse. All spelling it different too. There are many other mangas and anime with it as a name too. Like Eric being called just "One".
While it might sound silly to a person whose language it is. It still sound good globally though

* in case this came off as unclear. Calling someone just by their surname and not adding Mr/Ms etc comes off as rather rude, and is something more seen with historic power imbalances. Diesel and Ein are not called nicknames based on their surnames (Einchen, Einy?) but are straight up just referred to by their last names. It might be appropriate for Minsuk to know them as Herr or Mr Ein & Diesel, but Diesel and Ein really should be calling each other by their actual names. Maybe this gets lost in translation as some comics that are set in Europe have characters only use the first name, likely because this is the norm in the authors own country.

edit, meant to type "have characters only use the surname" ffs (▰˘◡˘▰)

Well I think it depends on where you are from. We dont call someone by their surnames at all. Just names. We however do call older people "uncle" or "aunt" though it sound different in my language. However when you DO say mrs/mr then you attach the surname and not name. And it usually is only used for professional proposes. So yeah. I think it all depends on where you live. Like its common for our natives here to name their kids "Precious" "Son" "Daughter" etc

You can not take any name you like in Germany! He must stand in the register and if not, a court checks whether the name is permissible!
Everything is possible in the USA! Also something like "Apple" (Gwyneth Paltrow child) .. you can not call your child "Apfel" in Germany! XD Or Peaches "Pfirsich" or "Blue Ivy" and "Saint West, North West, Chicago West" XDD
The judges in Germany would ask you if you are crazy! XD
Oder besser gesagt "Ob dunoch alle Latten am Zaun hast! :D hahaha

It was weird for me at first, too but I think Ein and Diesel aren't their real names.
They either use fake names because they're in hiding or Ein and Diesel are just nicknames. At least in south Germany it's quite common to call your friends and sometimes even your partner (if they really hate their given names ;) ) by their nicknames.

It seems likely that they are going by fake names, but this doesn't refute that their naming choices are odd. If they were hiding their identities, than to others they would still be called Mr/Herr Diesel, and call each other in private by their first names or a nickname. Bexan too is a bit of an odd choice, if the theme is that he has Russian heritage then this could have been linked to his name rather than calling him by what is presumably a rather rare surname with once again to titles or his family using more informal/personal names.

*no titles (not to)

Yep, it just seems a bit out of place to use surnames in informal relationships like those shown, or to reference a surname without a title. In regards to titled for first names, guess this differs. From my own experience it's usually only young children who use Auntie forename or Uncle forename rather than just calling them by their forename or whatever name they use as a forename, like a nickname or middle name.

It's a German word, but not exactly a name. It just means "A" or "One". Diesel is a surname though. Still a surname wouldn't be used without a title as that comes off as rude and as though a master is ordering their servant, and it's usage would denote a formal/unfamiliar/professional relationship. It's a shame, as the author was very good at representing European names in their previous series. I think we are assuming that "Ein" and "Diesel" are fake names, but even if this is the case, their usage isn't appropriate.

So I was re-reading the manga today and actually Ein talks about his name with the police officer (after Bexan and Diesel's fight). He's Korean, his surname is Lee and Ein is Germanized version of his Korean name or something: http://www.mangago.zone/read-manga/wolf_in_the_house/nmt/c015/12/ And maybe werewolves don't have surname so Diesel it's just Diesel.

Well spotted, however "Lee-ssi" would still make "Mr Ein" as you don't just say the surname without a title. Diesel might know him as Mr Ein, rather than his Korean name, but it seems odd that he doesn't call him by his first name. Diesel is a surname, and this too would carry a title, and it seems unusual for either wolf to only be known by their surnames for reasons already addressed. Japan seems one of the few places where calling someone just by their surname is acceptable and denotes respect, rather than it coming off as strange, rude or impersonal for a German setting.

I think that Ein is his first name (whatever exactly is that in Korean), maybe his Korean name sounds a bit like Ein and he decided to use more Germanic version when he was abroad (although I admit it sounds super weird to be called One). It's clearly stated that his surname is Lee and he is referred as Mr. Lee a few times by Minsuk. Later on Bexan and Minsuk start to call him Ein.
And Diesel is a surname for us, humans, but he is a werewolf/dog and you can totally name your dog just Diesel. As far the story goes no one of the werewolves has a surname, so I think it's wrong to assume that Diesel is his surname and his first name is a mystery.
OMG...SO HOT... ............