Submarine 707 v5
OctonionicNo, not really. But the art style changes partway through this volume, which caused speculation of the sort. Apparently, Ozawa was working as an engineer at Nippon Steel and Hino Motors as his main jobs, and drawing a weekly manga as a side-job only. To meet deadlines, he relied on an assistant to move from the sketching to inking phase, and the assistant died or was injured (sources disagree). This led to the style change, and possibly to abruptly concluding things.
As to the stories themselves, the finale of the Mu story comes pretty early in this volume. What follows is a tale that seems abruptly cut off, but has a few ideas that Ozawa later used in “Blue Submarine No. 6”. For example, the concept of the “P.S.G” seems almost trite today, but in 1965 it was a daring vision of the future.
I should mention that a character here, Professor Ramapo, is possibly named in honor of Hirai Tarou, who used the pen name Edogawa Ranpo, and who died in 1965, the year this story was written (and in which it takes place). Ranpo was a well-respected author, best known for “boy detective” stories that may very well have been an influence for Ozawa.
Speaking of names, two of the next names that appear are エイモス (Amos) and ケーン (Kane). I'm not entirely sure I got the spellings right: there's some argument to be made that “Amos” should be spelled “Eimos”, or that “Kane” should be spelled “Cain” (or perhaps “Caine”). Ultimately, these choices match what I've seen of Japanese transliterations for names such as USS Kane and AA-9 Amos.
Volume 5