@miner49er It's common in any form of media, for it to vanglorize their own culture. If this bothers you people, watching american action movies must be impossible... And the choice of picking Jack wasn't about him being the greatest warrior from Europe, it was about who had the best chance against Heracles.
And saying most mangas with inter cultural exchange are biased against western countries is...honestly just not true. Young Japanese seem to really like western stuff, it's usually very popular over there. As pointed before, of course they like to toot their own horn by making japanese stuff badass as fuck, but you really must not read mangas with cultural exchange if you think most are biased against western countries.
Also, while i do get some bias for japanese warriors from this manga, i don't think it's that strong, until now Sasaki was the only Japanese featured in a main role, there's not even japanese gods appearing. Might get more prominent now with the shinsengumi appearing and all, but i'd like to see more warriors from other places and gods from different cultures as well, we got thor from germanic and the rest are all greek, zeus, poseidon and heracles.
Edit: Just read the latest chapter, and i politely withdraw what i said about not seeing too much bias XD. I still think it's fine, a japanese author representing more japanese warriors is expected really i'd like it more if he were to be more diverse and pick heroes from all over the place like Fate (but representing them more as they were+manga badassery). Featuring more known characters for his audience makes sense too. Glad to see Shiva finally fighting though