(Ｕ 'ᴗ' Ｕ)

The mouth is ᴗ, LATIN SMALL LETTER BOTTOM HALF O: just the lower half of an o, a shallow arc, open at the top, that reads as a small, easy smile. Right beside it on each side, with no space in between, is an eye, a straight apostrophe ' (U+0027), the kind found on ordinary keyboards. Each eye is a short upright stroke. Both sit higher than ᴗ, and ᴗ itself fits within the lower half of the height of Ｕ. So the eyes and the mouth are packed into one tight cluster in the middle of the face. There are just two spaces, one between each Ｕ and the eye next to it. Those two Ｕ's are fullwidth capital letters set just inside the parentheses, and they look like ears hanging down beside the face, so the whole thing can be read as a floppy-eared dog. Notice that ᴗ has the same open-topped shape as Ｕ, only much smaller and shallower. On X it appeared right after おはようございます (ohayō gozaimasu, "good morning"). The same person has also used (Ｕ ˘ᴗ˘ Ｕ) on a different day. In that face the ˘ eyes are closed; here the ' eyes are open, as if looking straight at you.