"there are an enormous number of loan words (mostly from English)."
Actually, no. Most of the loan words are from Chinese, if you look at the full vocabulary of Japanese. Old Chinese. It's a huge part of the Japanese vocabulary.
Then you have a lot of loan words (from later times) from Portuguese, Dutch, and even German. And English. But even words like the word for beer (ビール), which sounds something like "beer-oo" isn't from English. It's from Dutch "bier".
In any case, the modern loan words are nearly always written in katakana, while loan words from traditional Chinese aren't. You don't see them as easily, while you can quickly spot modern loan words and there aren't _that_ many. Even though new loan words tend to come more from English nowadays.
Actually, no. Most of the loan words are from Chinese, if you look at the full vocabulary of Japanese. Old Chinese. It's a huge part of the Japanese vocabulary. Then you have a lot of loan words (from later times) from Portuguese, Dutch, and even German. And English. But even words like the word for beer (ビール), which sounds something like "beer-oo" isn't from English. It's from Dutch "bier".
In any case, the modern loan words are nearly always written in katakana, while loan words from traditional Chinese aren't. You don't see them as easily, while you can quickly spot modern loan words and there aren't _that_ many. Even though new loan words tend to come more from English nowadays.