Displaying both proximal and distal coxae, it is the closest mimic yet to Infirmamaxilla kurisu, hence the species name as an “ultimate” form. The considerably large amicula has numerous markings that resemble simplified Chinese and Japanese characters. Specimens were found preying on paper wrapped around shine muscat grapes at the Yau Ma Tei Fruit Market in Hong Kong. Rather than the finely textured integument that is present in others in the Kurisuphenax genus, K. ultimus has a polished integument on both sides. Species discovered and described by Kurisu.