101Leafy researched the game with the Hilltop Works fan translation patch, English translation by Cargodin
Mean Mug人面

Mean Mug is row 35 of the game's guilü table, with the element Earth. The battle screen reads (Shoot Tree!): it is weak to Tree.
It is on drop table 1, whose first weight gives all 64 rolls to nothing, so it never drops anything even though the table lists Shellfish Powder, Guilü Balls, and Men's Extract after it.
Guilü table: Fan Dog Mean Mug Bone Bug Lady
English translations by Cargodin for Hilltop Works Fan Translation Patch: https://www.patreon.com/hilltopworks/posts/kowloons-gate-160555525?collection=18503