This is it. The last Getter Robo series by Ken Ishikawa before his passing in 2006. The very last manga to continue the story of Getter and the Saotome labs started in the 1970s. I'll tell you now - this manga series ends on a cliffhanger. The magazine that it was published in, Super Robot Magazine, was discontinued midway through the series' run. Presumably, Ishikawa was going to continue the series, as the final page of the manga stated: "Getter Robo Arc Part 1: End". But sadly, that never came to be.
(Getter Robo Saga) Getter Robo Arc Volume 1 Chapter 1
I'd like to thank OtherSideofSky for translating this series and Getter Robo G. His work is top notch and his speed is just as good. And I'd like to thank everyone who donated to get this project going. Without you, this wouldn't have been possible. Thank you.
P.S. The reading order of Getter Robo Saga is as follows:
Getter Robo, Getter Robo G, Getter Robo Go, Shin Getter Robo, Getter Robo Arc