How to group Japanese and other non-Latin names in LongListSelector?

The short answer is: you add 96 to the unicode value of hiragana (ま) to get the equivalent katakana (マ).

You can determine if a character is hiragana by checking that it's unicode value falls in the range 3040-309F.

Unfortunately, as Noah mentions, many names are spelt using kanji: an alphabet of about 40,000 characters each with hiragana equivalents and many contextual to their surroundings. If you want to support those, you'll need to look for a Japanese language library to help you.

FYI, katakana is occasionally used to represent CAPITAL letters so that would explain their usage here. (Given Metro's lowercase preference, I would have thought katakana a better fit).

If you only want to support hiragana, here's something that should help:

const int KatakanaStartCode = 0x30A0;
const int HiraganaStartCode = 0x3040;
const int HiraganaEndCode = 0x309F;

private char GetGroupChar(string name)
{
    // Check for null/blank
    // Check for numbers, etc

    char firstChar = name[0];
    int firstCharCode = (int)firstChar;

    bool isHiragana = (HiraganaStartCode <= firstCharCode && 
        firstCharCode <= HiraganaEndCode);

    if (isHiragana)
    {
        char katakanaChar = (char)(firstCharCode + 
            (KatakanaStartCode - HiraganaStartCode));

        return katakanaChar;
    }

    return Char.ToLowerInvariant(firstChar);
}

And then:

string name = "またな たなかあ";

char s = GetGroupChar(name);

Debug.WriteLine(s); // マ