Sonoyama also did other strips, including Ganbare Gonbe (1958-1992), Hana no Kakaricho (1969-1982), and Gatapishi (1979-1992). But one of the most unusual is probably this one, and I happened to have a copy of it.
It's called Kokkyo no Futari (Two Guys on the Border). It's a 32-page booklet that Sonoyama published himself in 1962. It's a series of one-panel cartoons featuring two guards on the opposing sides and their friendship. I took the liberty of scanning some of the pages below, along with the letter Sonoyama himself wrote (in English), signed and attached to the booklet.









