He started out as a manga artist at the young age of 13, when he created The Strange Star Cluster (怪奇星団) in 1948.
His turning point came in 1957, when he created Maboroshi Tantei (まぼろし探偵, Phantom Detective) (which was adapted into a tokusatsu TV series in 1959).
With Kuwata in jail, co-creator Hirai got other manga artists to finish the final issue, but wasn't satisfied with it.
Nevertheless, Kuwata, released from prison shortly thereafter, continued his manga work well into the 1970s, but also ran into depression and alcoholism.
He also occasionally got back into manga work, and in 1992, he agreed to do his own version of the final issue of 8 Man, upon being asked by co-creator/friend Kazumasa Hirai.