But if the actual Buddhism realm is Naraka, why call the chapter Naraku. I guess in Japanese it probably works better that way when Kaido's attack or something, but in English Ragnaraka would sound fine.
Well Naraka isn't a Japanese word. Also, like I explained before, Naraku has multiple meanings, and that is probably why Oda chose it. It isn't like he explicitly chose it because of Naraka or else he could have called it Naraka.
I read that Ragu means to drag or lug something around. Does it also mean to drag them to hell?
Well Ragu doesn't mean that, but the kanji (chinese character) used for that part of the word is the one used for "hiku" which generally means "to pull, to tug" and things of that nature. They also use it the same way we say "catch a cold."
Mangakas love to give attacks English or other western language names but they also write out the name in kanji which essentially describes the nature of the attack or provides a second meaning.
In this case the name was essentially Ragnaraku but the kanji could imply pulling down to naraka or pulling down to rock bottom.
What makes things even harder is that these Chinese characters will share the same pronunciations and meanings across multiple words but change based on what noun they are interacting with or what meaning you want to convey.
So for instance the word you use for "pluck a guitar string" is also "hiku" but the kanji is different. In this same way, "hiku" shares a similar meaning with a 3rd kanji that means "to move back, draw back, recede." This 3rd kanji also has a unique pronunciation that gives it a different meaning which can mean "to withdraw (from a superior)" or "to concede."
There are a lot of meanings and connections that can be made if you have the knowledge and think there are connections to be made. Oda probably isn't going to come out and say "this literally has only 1 meaning and everything else is wrong" and that is why fans enjoy guessing at what Oda intended and if there are hidden meanings in things.
–- Update From New Post Merge ---
@Kaworu:
Yeah, though interestingly they have different names, the Giants' one is Hakoku, the dual Yonkou one is apparently Hakai. Still a clear reference visually, I think it'll all tie up neatly at Elbaf.
These are essentially the same attacks, the "Ha" is the same, but the "koku" from the Giants means "country" and the "kai" from the Emperors means "sea."
If I were to explain the Giants' attack could be "Champions/Titleholders of their country" and the Emperors' attack is "Rulers/Conquerors of the sea," so it is at least a couple steps or levels higher than the Giants' attack.