Tsu (hiragana: つ, katakana: ツ) is one of the Japanese kana, each of which represents one mora.

Both are phonemically /tɯ/, reflected in the Nihon-shiki and Kunrei-shiki Romanization tu, although for phonological reasons, the actual pronunciation is [t͡sɯᵝ] ⓘ, reflected in the Hepburn romanization tsu.

They are mainly used to indicate consonant gemination and commonly used at the end of lines of dialogue in fictional works as a symbol for a glottal stop.

In the Ainu language, it can be written with a handakuten (which can be entered into a computer as either one character (ツ゚) or two combined characters (ツ゜) to represent the sound [tu͍], which is interchangeable with the katakana ト゚.

The katakana form has become popular as an emoticon in the Western world due to its resemblance to a smiling face and as part of a "shrug" emoticon, known alternatively as Shruggie, rendered as:  ¯\_(ツ)_/¯ .