Kinokojin

Kinokojin (キノコジン): A mushroom cyborg augmented with a special mushroom with near unlimited energy and able to spew a deadly spore mist. When Tsukuba investigates Devil's Mountain Pass, Kinokojin mimics Yukie's appearance to kill the Kamen Rider when his guard is down while visiting a girl named Kumikoin the hospital. However, exposed by his cold hands, Kinokojin uses his spores to manipulate Tsukuba into drowning himself. But the seawater negates the spores and Tsukuba assume his Kamen Rider form and causes Kinokojin to dissolve with his Sky Kick.