Earlier quoted context omitted.
Also, not to be confused with "一", which is a different thing entirely……
This one is U+4E00, CJK Unified Ideograph-4E00. So it's a common character between Chinese, Japanese, and Korean. This should be "one" in all three. And it does technically look a little different than a dash: https://unicodeplus.com/U+4E00
ー