def convert_katakana_to_hiragana(in_str: str) -> str:
    """Convert katakana characters in a given string to their corresponding hiragana characters.

    Args:
        in_str: A string.

    Returns:
        A string where katakana characters have been converted into hiragana.
    """
    return "".join(chr(ord(ch) - 96) if ("ァ" <= ch <= "ン") else ch for ch in in_str)