Masako Tomii has been credited on Pokémon Trading Card Game cards since 2023, with work appearing through 2025. Credits are concentrated in the Scarlet & Violet series, with appearances in sets such as Obsidian Flames, Paradox Rift, and Twilight Masquerade.
The illustrations favor vibrant, contrasting palettes and a stylized, cartoonish finish, often organized around balanced layouts with occasional dynamic motion. Moods skew whimsical and cheerful, with energetic staging and clear central subjects. Among the most sought-after cards illustrated by Masako Tomii is Yveltal (sv4-205).