The glyph is not a composition. Its width in East Asian texts is determined by its context. It can be displayed wide or narrow. In bidirectional text it is written from left to right. When changing direction it is not mirrored. The word that U+0438 forms with similar adjacent characters prevents a line break inside it. The glyph can be confused with one other glyph.
The Wikipedia has the following information about this codepoint:
I (И и; italics: И и or И и; italics: Ии) is a letter used in almost all Cyrillic alphabets with the exception of Belarusian.
It commonly represents either the close front unrounded vowel /i/ (e.g., in Russian), like the pronunciation of ⟨i⟩ in "machine", or the near-close near-front unrounded vowel /ɪ/, (e.g., in Ukrainian), like the pronunciation of ⟨i⟩ in "bin".