@starburst98 @Akemua @Dankdevice I wouldn't have said anything, but as long as there's an argument--
I'm often in favour of not translating some relationship-words, particularly brother-sister ones, because you lose the honorifics and, with them, important info about tone and the kind of relationship you're dealing with. Onii-san is quite different from onii-chan and it's hard to capture that in English--heck, even just saying "brother" in English tends to feel weird, to the point where it almost flows better left in Japanese.
But otou-san doesn't really have that kind of thing going. It's pretty much just standard "father", and that's not an unnatural thing to say in English. And does
anyone say "otou-sama" if they're not sitting on tatami in a big old-school Japanese mansion? Maybe if he
did say "sama" you could consider not translating, but not when someone's just talking normally.
You don't gain anything as far as I can tell from not translating it, but you do lose something, such as a fair number of readers not knowing what it means, and loss of fluidity because you just stuck in an untranslated word. I've been reading large amounts of manga for more than
20 years, and I was still like "What? Oh, right, that means father doesn't it--pretty sure" rather than being able to read naturally.
And I think the argument "Oh, all the
real manga-readers will know so screw the n00bs" is a stupid, elitist one. If a choice won't make things better for anyone but will make things worse for some, it's not a good choice. Sorry, but this is "all according to keikaku" type stuff as people have been saying. Doubtless the people who did that thought that somehow some important nuance was lost by translating "keikaku", but they were mistaken.