For the original Resident Evil, Shimogama was responsible for the creation of texture files to be used as character/creature skins. He is known to have been responsible for the creation of the Hunter A's texture file, which he designed to be recognisably female.
For Resident Evil 2, Shimogama worked alongside Isao Ōishi in drawing concept art; Shimogama handled creature proposals while Ōishi handled characters. Consequently, Shimogama is responsible for the designs of creatures such as the Licker and Plant 43. Other ideas for the game which were rejected included alternate bosses like Zeiram and Golgotha, a G-Virus infected Annette Birkin, and zombified primates with designs alternating between monkey and ape.