NTT Docomo i-mode emojis started as monochrome pixel art, but have been available as vector graphics as well for a while now. Since 2012, when Android 4.4 introduced color emojis, KDDI au EZweb has been using the same glyphs, whereas Softbank (with Ymobile, E-Mobile, Willcom, Disney Mobile) continues to use its own design (as do all non-Japanese vendors). In 2014, the set was updated to cover all Unicode emojis of the time. As far as I know there have been no subsequent updates (neither for Unicode 8.0 and 9.0 nor the emoji sequences from UTR#51),
These shall hence form the base of a variety of fonts and picture sets.