Yn is an archaic Cyrillic letter. It looks like the Cyrillic letter Psi (Ѱ ѱ) with its upper half turned upside down, but the letter mostly looks like an arrow pointing vertically up (↑).
It was used in the Romanian Cyrillic alphabet, where it represented the sounds pronounced as /[ɨn]/, pronounced as /[ɨm]/, and pronounced as /[ɨ]/ at the beginning of words.[1] In the modern Romanian alphabet it is replaced by (în), (îm), or (î).
As few fonts contain the appropriate glyphs, the Upwards Arrow (↑) is sometimes substituted. The notable fonts that have included this glyph are FreeSerif and Segoe UI (since Windows 8).