Kimiya Masago is credited on Pokémon Trading Card Game cards since 2001, with credits extending through 2006. In this index, Masago appears on 25 cards, concentrated in the E-Card and Neo series. Set appearances are led by Skyridge, Expedition Base Set, and Neo Discovery, with additional credits in Legend Maker and Neo Revelation.
The work is primarily traditional illustration, often built around vibrant, contrasting color palettes and balanced, focused compositions. Across the catalogue, moods frequently register as dynamic and mysterious, with occasional playful or intense notes, and action-forward staging that keeps the subject clear in the frame. A representative card is Umbreon (Neo Discovery).