24060
The sentence is

二人間がしっくり行かない

i'm confused when to use ににん and when to use ふたり
CC BY-SA 3.0
2015-04-30T17:34:05.303
24043
2015-05-01T07:57:35.467
2015-04-30T18:06:21.390
78
9639
question
kanji
What's the reading of 二人 in this sentence?
It's ふたり. You always use ふたり when indicating a group of two people or their
relation. Note that you can use both ふたり and ににん when just counting people.  
One can tell 二人 in this sentence is not for counting number because of 間. It
reads かん and means relation.

> 二人間: relation between those two  
>  日米間: Japan-America relation  
>  先生と学生間: between a teach and a student  
>  夫婦間: between a married couple
CC BY-SA 3.0
2015-04-30T21:19:10.683
24050
2015-05-01T03:20:32.320
2015-05-01T03:20:32.320
9980
9980
24043
answer
First, your example is likely a mistake for

```

    二人の間がしっくり行かない
    
```

The original is substandard, if not wrong. And yes, 「二人」is pronounced「ふたり」in
this case.

So, when is「二人」pronounced「ににん」? I don't think it's easy to come up with a
simple set of rules, but at least if the sequence . . . 五人、四人、三人、二人 works down
to 2, then it's pronounced「ににん」. For example, 「二人前」(two persons' portion).
Why? Because in today's Japanese, the Chinese-based pronunciation (に、さん、し、ご、.
. . ) is used for the number when the word is regarded as number + units, so
"three persons", "five kilometers", etc. are pronounced さんにん、ごキロメートル, etc. On
the other hand, 「ふたり」is no longer regarded as number plus units. (It
historically is, so there used to be みたり、よたり、いつたり、むたり、after ひとり and ふたり.)

「ひとり」is a bit different. There still is a strong tendency to prefer ひとり to
いちにん. So, 「一人前」can be pronounced ひとりまえ.

Finally, what's wrong with「二人間」? Isn't it like「日米間｣? Well, I don't have a
logical answer to it, but we simply don't say ｢二人間」. Perhaps that's because
that would require the Chinese-based pronunciation ににん in order for it to
precede 間, but when talking about two persons we almost always refer to ふたり,
not ににん.
CC BY-SA 3.0
2015-05-01T07:57:35.467
24060
2015-05-01T07:57:35.467
9983
24043
answer