A gifted artist, Kuwata 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 Phantom Detective (まぼろし探偵?) (which was adapted into a tokusatsu TV series in 1959). Since then, Kuwata devoted himself to creating science fiction/superhero adventures. His most famous was 8 Man, which he co-created with writer Kazumasa Hirai.
Unfortunately, in 1965, when he was to finish the final issue of 8 Man, he was arrested for possessing a handgun (he had contemplated suicide). With Kuwata in jail, co-creator Hirai got other manga artists to finish the final issue, but wasn't satisfied with it. It was published in a manga magazine, but has never before been reprinted.
Nevertheless, Kuwata, released from prison shortly thereafter, continued his manga work well into the 1970s, but also ran into depression and alcoholism. In 1977, he had an epiphany and converted to Buddhism. He has since done beautiful art books about the life of Buddha. 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.