The Mystery of Numbers Written in Blood (Chi de Kaita Suuji no Nazo- 血で書いた数字の謎) - S1.E20

Voltes team tried to figure out what the numbers written on the cloth mean. The figure turned out to be a pulsating wave frequency. Dr. Gou transmitted this wave by using a mini transmitter and by tracking the wave, Voltes can trace his whereabouts. Meanwhile Zuuru created Zoru Geru, an amoeba-like robot that can heal itself or even change form. When he failed to defeat Voltes, Zuuru was tortured by Heinell as punishment.