[steven]

I'm not confusing diphthongs with digraphs. I know what 音節 is and what it means.

I realize that some people say outright that there are no diphthongs in Japanese. Some people will say that there are. I say that there are and I don't think I'm going to change my stance on that.

ちゃ　ちょ　and ちゅ are in no way two syllables. (I'm not sure if that's what you were implying or not) With that logic, the word "choose" would be two syllables (unless you want to throw in one more for good measure because of the "silent e"). I would argue that when spoken normally they are not diphthongs as well. I think we agree on that.

Let me get this straight- you are saying that the word 牛肉 is four or possibly five syllables? This is because the ぎゅ is 2 syllables by your logic... plus a syllable for the う then there are a syllable each for に　and く, right?

Here's how I see it: ぎゅう is one syllable...　as is に and as is く (that makes three). ぎゅう also happens to have a diphthong in it in my opinion. It's similar to that which is in the words "cute" and "ambiguous", which are one and four syllables respectively.

For another example, let's take a look at the words 病院 and 美容院. I say 病院 has 2 syllables and 美容院 has three syllables (don't worry, I'm not just counting the kanji). To pronounce 病院 with three syllables would give you 美容院, which is a completely different word with a completely different meaning. (I am implying that the extra syllable is added to びょう makes びよう).

The same thing goes for 牛 and 義勇. 牛 being one syllable and 義勇 being two. Those meanings are also very different.

Not only that, but the characters や　ゆ　and よ by themselves can be considered diphthongs in my opinion (depending on how they are spoken). In combination with certain kana (like the ones I explained above) make something that is definitely a diphthong as I understand it. As far as syllable stuff goes, to add syllables in the places I showed is to say a completely different word which can confuse things and distort the language. To be clear, that's why I brought this up to begin with. A lot of beginners don't make this distinction (I'm talking about native English speakers) even though extremely similar sounds exist in our native language. It's a simple mistake which can be avoided with a little explanation as far as I can tell.