Kana ligature
In the Japanese writing system kana ligatures (Japanese: 仮名合字, Hepburn: kana gōji) are typographic ligatures in the kana writing system, both hiragana and katakana. These are now obsolete, and almost none are represented in standard character encodings. The only widely available ones are the hiragana yori (ゟ, from より) and the katakana koto (ヿ, from コト). They are also known as gōryaku-kana (合略仮名, literally "combined abbreviated kana") and tsuzuki-kana (続き仮名, literally "connected kana").
History
These characters were widely used until a spelling reform of 1900 decreed that each sound (mora) would be represented by one (kana) character. They were not represented in computer character encodings until JIS X 0213:2000 (JIS2000) added yori and koto.
In the 21st century, in modern Internet slang, some ligatures are made using existing characters, such as 托 for キモ in 托い for kimoi (キモい, gross) (托い is not a word, but it would be pronounced takui, and mean "entrust-adjective") and ル for ノレ in モルール for monorēru (モノレール, monorail) (モルール would be pronounced morūru).