absorbent sheet; meat pad; soaker pad
A thin absorbent pad placed under raw meat, fish, or in sushi containers to soak up excess liquid. Often called a 'meat pad' or 'absorbent pad' in English. The Japanese term is wasei-eigo from 'Dracula mat', evoking the idea of sucking up blood/liquid.
wasei-eigo (Japanese-coined English), from Dracula mat
See also: ドリップ吸水シート
There is an absorbent sheet laid at the bottom of the meat pack.
Thanks to the absorbent pad, water doesn't leak from the sashimi pack.