What does KÜ stand for? 

Ku

く, in hiragana, or ク in katakana, is one of the Japanese kana, which each represent one mora. Both represent, and their shapes come from the kanji 久. This kana may have a dakuten added, transforming it into ぐ in hiragana, グ in katakana, and gu in Hepburn romanization. The dakuten's addition also changes the sound of the syllable represented, to in initial positions, and varying between and in the middle of words. A handakuten does not occur with ku in normal Japanese text, but it may be used by linguists to indicate a nasal pronunciation. In the Ainu language, the katakana ク can be written as small ㇰ, representing a final k sound as in アイヌイタㇰ Ainu itak. This was developed along with other extended katakana to represent sounds in Ainu that are not found in standard Japanese katakana.

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