Sublieutenant Mitsuo Onishi's Crawler Driver was involved in the pursuit of Renée Messier and Alec Hall after the Japanese attack on Io. As they closed for the kill, he warned Onishi that the ground temperature was climbing and had reached 25°C. Onishi dismissed his concerns as the crawler rated safe for 150°C and ordered him to continue the advance. This decision was unfortunate since the crawler drove into a hotspot, broke the surface and plunged into the boiling sulphur killing both.